diff --git a/src/Mod/Sketcher/App/Constraint.cpp b/src/Mod/Sketcher/App/Constraint.cpp
index 416b2ca9d6..24d0959f84 100644
--- a/src/Mod/Sketcher/App/Constraint.cpp
+++ b/src/Mod/Sketcher/App/Constraint.cpp
@@ -53,7 +53,8 @@ Constraint::Constraint()
   Third(GeoUndef),
   ThirdPos(none),
   LabelDistance(10.f),
-  LabelPosition(0.f)
+  LabelPosition(0.f),
+  isDriving(true)
 {
 }
 
@@ -69,7 +70,8 @@ Constraint::Constraint(const Constraint& from)
   Third(from.Third),
   ThirdPos(from.ThirdPos),
   LabelDistance(from.LabelDistance),
-  LabelPosition(from.LabelPosition)
+  LabelPosition(from.LabelPosition),
+  isDriving(from.isDriving)
 {
 }
 
@@ -109,7 +111,8 @@ void Constraint::Save (Writer &writer) const
     << "Third=\""                       <<  Third               << "\" "
     << "ThirdPos=\""                    <<  (int) ThirdPos      << "\" "
     << "LabelDistance=\""               <<  LabelDistance       << "\" "
-    << "LabelPosition=\""               <<  LabelPosition       << "\" />"
+    << "LabelPosition=\""               <<  LabelPosition       << "\" "
+    << "IsDriving=\""                   <<  (int)isDriving      << "\" />"
     << std::endl;
 }
 
@@ -140,4 +143,7 @@ void Constraint::Restore(XMLReader &reader)
 
     if (reader.hasAttribute("LabelPosition"))
         LabelPosition = (float)reader.getAttributeAsFloat("LabelPosition");
+   
+    if (reader.hasAttribute("IsDriving"))
+        isDriving = (bool)reader.getAttributeAsInteger("IsDriving");
 }
diff --git a/src/Mod/Sketcher/App/Constraint.h b/src/Mod/Sketcher/App/Constraint.h
index e8bbfe67ef..82737de95d 100644
--- a/src/Mod/Sketcher/App/Constraint.h
+++ b/src/Mod/Sketcher/App/Constraint.h
@@ -95,6 +95,7 @@ public:
     PointPos ThirdPos;
     float LabelDistance;
     float LabelPosition;
+    bool isDriving;
 };
 
 } //namespace Sketcher
diff --git a/src/Mod/Sketcher/App/Sketch.cpp b/src/Mod/Sketcher/App/Sketch.cpp
index 9dff30f718..3b519e4d54 100644
--- a/src/Mod/Sketcher/App/Sketch.cpp
+++ b/src/Mod/Sketcher/App/Sketch.cpp
@@ -94,6 +94,11 @@ void Sketch::clear(void)
     for (std::vector<GeoDef>::iterator it = Geoms.begin(); it != Geoms.end(); ++it)
         if (it->geo) delete it->geo;
     Geoms.clear();
+    
+    // deleting the non-Driving constraints copied into this sketch
+    //for (std::vector<Constraint *>::iterator it = NonDrivingConstraints.begin(); it != NonDrivingConstraints.end(); ++it)
+    //    if (*it) delete *it;
+    Constrs.clear();
 
     GCSsys.clear();
     isInitMove = false;
@@ -121,9 +126,9 @@ int Sketch::setUpSketch(const std::vector<Part::Geometry *> &GeoList,
         Geoms[i].external = true;
 
     // The Geoms list might be empty after an undo/redo
-    if (!Geoms.empty())
+    if (!Geoms.empty()) {                 
         addConstraints(ConstraintList);
-
+    }
     GCSsys.clearByTag(-1);
     GCSsys.declareUnknowns(Parameters);
     GCSsys.initSolution();
@@ -630,24 +635,69 @@ int Sketch::addConstraint(const Constraint *constraint)
     if(int(Geoms.size()) <= 0)
         throw Base::Exception("Sketch::addConstraint. Can't add constraint to a sketch with no geometry!");
     int rtn = -1;
+    
+    ConstrDef c;
+    c.constr=const_cast<Constraint *>(constraint);
+    c.driving=constraint->isDriving;
+        
     switch (constraint->Type) {
     case DistanceX:
-        if (constraint->FirstPos == none) // horizontal length of a line
-            rtn = addDistanceXConstraint(constraint->First,constraint->Value);
-        else if (constraint->Second == Constraint::GeoUndef) // point on fixed x-coordinate
-            rtn = addCoordinateXConstraint(constraint->First,constraint->FirstPos,constraint->Value);
-        else if (constraint->SecondPos != none) // point to point horizontal distance
+        if (constraint->FirstPos == none){ // horizontal length of a line
+            c.value = new double(constraint->Value);
+            if(c.driving)
+                FixParameters.push_back(c.value);            
+            else
+                Parameters.push_back(c.value);
+            rtn = addDistanceXConstraint(constraint->First,c.value);
+        }
+        else if (constraint->Second == Constraint::GeoUndef) {// point on fixed x-coordinate
+            c.value = new double(constraint->Value);
+            if(c.driving)
+                FixParameters.push_back(c.value);            
+            else
+                Parameters.push_back(c.value);            
+            
+            rtn = addCoordinateXConstraint(constraint->First,constraint->FirstPos,c.value);
+            }
+        else if (constraint->SecondPos != none) {// point to point horizontal distance
+            c.value = new double(constraint->Value);
+            if(c.driving)
+                FixParameters.push_back(c.value);            
+            else
+                Parameters.push_back(c.value);
+            
             rtn = addDistanceXConstraint(constraint->First,constraint->FirstPos,
-                                         constraint->Second,constraint->SecondPos,constraint->Value);
+                                         constraint->Second,constraint->SecondPos,c.value);
+        }
         break;
     case DistanceY:
-        if (constraint->FirstPos == none) // vertical length of a line
-            rtn = addDistanceYConstraint(constraint->First,constraint->Value);
-        else if (constraint->Second == Constraint::GeoUndef) // point on fixed y-coordinate
-            rtn = addCoordinateYConstraint(constraint->First,constraint->FirstPos,constraint->Value);
-        else if (constraint->SecondPos != none) // point to point vertical distance
+        if (constraint->FirstPos == none){ // vertical length of a line
+            c.value = new double(constraint->Value);
+            if(c.driving)
+                FixParameters.push_back(c.value);            
+            else
+                Parameters.push_back(c.value);
+            rtn = addDistanceYConstraint(constraint->First,c.value);
+        }
+        else if (constraint->Second == Constraint::GeoUndef){ // point on fixed y-coordinate
+            c.value = new double(constraint->Value);
+            if(c.driving)
+                FixParameters.push_back(c.value);            
+            else
+                Parameters.push_back(c.value);
+
+            rtn = addCoordinateYConstraint(constraint->First,constraint->FirstPos,c.value);
+        }
+        else if (constraint->SecondPos != none){ // point to point vertical distance
+            c.value = new double(constraint->Value);
+            if(c.driving)
+                FixParameters.push_back(c.value);            
+            else
+                Parameters.push_back(c.value);
+            
             rtn = addDistanceYConstraint(constraint->First,constraint->FirstPos,
-                                         constraint->Second,constraint->SecondPos,constraint->Value);
+                                         constraint->Second,constraint->SecondPos,c.value);
+        }
         break;
     case Horizontal:
         if (constraint->Second == Constraint::GeoUndef) // horizontal line
@@ -680,11 +730,17 @@ int Sketch::addConstraint(const Constraint *constraint)
             rtn = addPerpendicularConstraint(constraint->First,constraint->Second);
         } else {
             //any other point-wise perpendicularity
+            c.value = new double(constraint->Value);
+            if(c.driving)
+                FixParameters.push_back(c.value);            
+            else
+                Parameters.push_back(c.value);
+            
             rtn = addAngleAtPointConstraint(
                         constraint->First, constraint->FirstPos,
                         constraint->Second, constraint->SecondPos,
                         constraint->Third, constraint->ThirdPos,
-                        constraint->Value, constraint->Type);
+                        c.value, constraint->Type);
         }
 
 
@@ -697,46 +753,101 @@ int Sketch::addConstraint(const Constraint *constraint)
             rtn = addTangentConstraint(constraint->First,constraint->Second);
         } else {
             //any other point-wise tangency (endpoint-to-curve, endpoint-to-endpoint, tangent-via-point)
+            c.value = new double(constraint->Value);
+            if(c.driving)
+                FixParameters.push_back(c.value);            
+            else
+                Parameters.push_back(c.value);
+            
             rtn = addAngleAtPointConstraint(
                         constraint->First, constraint->FirstPos,
                         constraint->Second, constraint->SecondPos,
                         constraint->Third, constraint->ThirdPos,
-                        constraint->Value, constraint->Type);
+                        c.value, constraint->Type);
         }
         break;
     case Distance:
-        if (constraint->SecondPos != none) // point to point distance
+        if (constraint->SecondPos != none){ // point to point distance
+            c.value = new double(constraint->Value);
+            if(c.driving)
+                FixParameters.push_back(c.value);            
+            else
+                Parameters.push_back(c.value);            
             rtn = addDistanceConstraint(constraint->First,constraint->FirstPos,
                                         constraint->Second,constraint->SecondPos,
-                                        constraint->Value);
-        else if (constraint->Second != Constraint::GeoUndef) {
-            if (constraint->FirstPos != none) // point to line distance
-                rtn = addDistanceConstraint(constraint->First,constraint->FirstPos,
-                                            constraint->Second,constraint->Value);
-            else // line to line distance (not implemented yet)
-                rtn = addDistanceConstraint(constraint->First,constraint->Second,constraint->Value);
+                                        c.value);
+        }
+        else if (constraint->Second != Constraint::GeoUndef) {
+            if (constraint->FirstPos != none) { // point to line distance
+                c.value = new double(constraint->Value);
+                if(c.driving)
+                    FixParameters.push_back(c.value);            
+                else
+                    Parameters.push_back(c.value);
+                rtn = addDistanceConstraint(constraint->First,constraint->FirstPos,
+                                            constraint->Second,c.value);
+            }
+        }
+        else {// line length
+            c.value = new double(constraint->Value);
+            if(c.driving)
+                FixParameters.push_back(c.value);            
+            else
+                Parameters.push_back(c.value);  
+            
+            rtn = addDistanceConstraint(constraint->First,c.value);
         }
-        else // line length
-            rtn = addDistanceConstraint(constraint->First,constraint->Value);
         break;
     case Angle:
         if (constraint->Third != Constraint::GeoUndef){
+            c.value = new double(constraint->Value);
+            if(c.driving)
+                FixParameters.push_back(c.value);            
+            else
+                Parameters.push_back(c.value); 
+            
             rtn = addAngleAtPointConstraint (
                         constraint->First, constraint->FirstPos,
                         constraint->Second, constraint->SecondPos,
                         constraint->Third, constraint->ThirdPos,
-                        constraint->Value, constraint->Type);
-        } else if (constraint->SecondPos != none) // angle between two lines (with explicit start points)
+                        c.value, constraint->Type);
+        } else if (constraint->SecondPos != none){ // angle between two lines (with explicit start points)
+            c.value = new double(constraint->Value);
+            if(c.driving)
+                FixParameters.push_back(c.value);            
+            else
+                Parameters.push_back(c.value); 
+            
             rtn = addAngleConstraint(constraint->First,constraint->FirstPos,
-                                     constraint->Second,constraint->SecondPos,constraint->Value);
-        else if (constraint->Second != Constraint::GeoUndef) // angle between two lines
-            rtn = addAngleConstraint(constraint->First,constraint->Second,constraint->Value);
-        else if (constraint->First != Constraint::GeoUndef) // orientation angle of a line
-            rtn = addAngleConstraint(constraint->First,constraint->Value);
+                                     constraint->Second,constraint->SecondPos,c.value);
+        }
+        else if (constraint->Second != Constraint::GeoUndef){ // angle between two lines
+            c.value = new double(constraint->Value);
+            if(c.driving)
+                FixParameters.push_back(c.value);            
+            else
+                Parameters.push_back(c.value); 
+            rtn = addAngleConstraint(constraint->First,constraint->Second,c.value);
+        }
+        else if (constraint->First != Constraint::GeoUndef) {// orientation angle of a line
+            c.value = new double(constraint->Value);
+            if(c.driving)
+                FixParameters.push_back(c.value);            
+            else
+                Parameters.push_back(c.value); 
+            rtn = addAngleConstraint(constraint->First,c.value);
+        }
         break;
     case Radius:
-        rtn = addRadiusConstraint(constraint->First, constraint->Value);
+    {
+        c.value = new double(constraint->Value);
+        if(c.driving)
+            FixParameters.push_back(c.value);            
+        else
+            Parameters.push_back(c.value); 
+        rtn = addRadiusConstraint(constraint->First, c.value);
         break;
+    }
     case Equal:
         rtn = addEqualConstraint(constraint->First,constraint->Second);
         break;
@@ -766,62 +877,76 @@ int Sketch::addConstraint(const Constraint *constraint)
         }
         break;
     case SnellsLaw:
+    {
+        c.value = new double(constraint->Value);
+        c.secondvalue = new double(constraint->Value);
+
+        if(c.driving) {
+            FixParameters.push_back(c.value);
+            FixParameters.push_back(c.secondvalue);            
+        }
+        else {
+            Parameters.push_back(c.value);
+            Parameters.push_back(c.secondvalue);
+        }
+
         //assert(constraint->ThirdPos==none); //will work anyway...
         rtn = addSnellsLawConstraint(constraint->First, constraint->FirstPos,
                                      constraint->Second, constraint->SecondPos,
                                      constraint->Third,
-                                     constraint->Value);
+                                     c.value, c.secondvalue);
+    }
         break;
     case None:
         break;
     }
+    
+    Constrs.push_back(c);
     return rtn;
 }
 
 int Sketch::addConstraints(const std::vector<Constraint *> &ConstraintList)
 {
     int rtn = -1;
+
     for (std::vector<Constraint *>::const_iterator it = ConstraintList.begin();it!=ConstraintList.end();++it)
         rtn = addConstraint (*it);
 
     return rtn;
 }
 
-int Sketch::addCoordinateXConstraint(int geoId, PointPos pos, double value)
+int Sketch::addCoordinateXConstraint(int geoId, PointPos pos, double * value)
 {
     geoId = checkGeoId(geoId);
 
     int pointId = getPointId(geoId, pos);
 
     if (pointId >= 0 && pointId < int(Points.size())) {
-        double *val = new double(value);
-        FixParameters.push_back(val);
+
         GCS::Point &p = Points[pointId];
         int tag = ++ConstraintsCounter;
-        GCSsys.addConstraintCoordinateX(p, val, tag);
+        GCSsys.addConstraintCoordinateX(p, value, tag);
         return ConstraintsCounter;
     }
     return -1;
 }
 
-int Sketch::addCoordinateYConstraint(int geoId, PointPos pos, double value)
+int Sketch::addCoordinateYConstraint(int geoId, PointPos pos, double * value)
 {
     geoId = checkGeoId(geoId);
 
     int pointId = getPointId(geoId, pos);
 
     if (pointId >= 0 && pointId < int(Points.size())) {
-        double *val = new double(value);
-        FixParameters.push_back(val);
         GCS::Point &p = Points[pointId];
         int tag = ++ConstraintsCounter;
-        GCSsys.addConstraintCoordinateY(p, val, tag);
+        GCSsys.addConstraintCoordinateY(p, value, tag);
         return ConstraintsCounter;
     }
     return -1;
 }
 
-int Sketch::addDistanceXConstraint(int geoId, double value)
+int Sketch::addDistanceXConstraint(int geoId, double * value)
 {
     geoId = checkGeoId(geoId);
 
@@ -830,15 +955,12 @@ int Sketch::addDistanceXConstraint(int geoId, double value)
 
     GCS::Line &l = Lines[Geoms[geoId].index];
 
-    FixParameters.push_back(new double(value));
-    double *diff = FixParameters[FixParameters.size()-1];
-
     int tag = ++ConstraintsCounter;
-    GCSsys.addConstraintDifference(l.p1.x, l.p2.x, diff, tag);
+    GCSsys.addConstraintDifference(l.p1.x, l.p2.x, value, tag);
     return ConstraintsCounter;
 }
 
-int Sketch::addDistanceYConstraint(int geoId, double value)
+int Sketch::addDistanceYConstraint(int geoId, double * value)
 {
     geoId = checkGeoId(geoId);
 
@@ -847,15 +969,12 @@ int Sketch::addDistanceYConstraint(int geoId, double value)
 
     GCS::Line &l = Lines[Geoms[geoId].index];
 
-    FixParameters.push_back(new double(value));
-    double *diff = FixParameters[FixParameters.size()-1];
-
     int tag = ++ConstraintsCounter;
-    GCSsys.addConstraintDifference(l.p1.y, l.p2.y, diff, tag);
+    GCSsys.addConstraintDifference(l.p1.y, l.p2.y, value, tag);
     return ConstraintsCounter;
 }
 
-int Sketch::addDistanceXConstraint(int geoId1, PointPos pos1, int geoId2, PointPos pos2, double value)
+int Sketch::addDistanceXConstraint(int geoId1, PointPos pos1, int geoId2, PointPos pos2, double * value)
 {
     geoId1 = checkGeoId(geoId1);
     geoId2 = checkGeoId(geoId2);
@@ -868,17 +987,14 @@ int Sketch::addDistanceXConstraint(int geoId1, PointPos pos1, int geoId2, PointP
         GCS::Point &p1 = Points[pointId1];
         GCS::Point &p2 = Points[pointId2];
 
-        FixParameters.push_back(new double(value));
-        double *difference = FixParameters[FixParameters.size()-1];
-
         int tag = ++ConstraintsCounter;
-        GCSsys.addConstraintDifference(p1.x, p2.x, difference, tag);
+        GCSsys.addConstraintDifference(p1.x, p2.x, value, tag);
         return ConstraintsCounter;
     }
     return -1;
 }
 
-int Sketch::addDistanceYConstraint(int geoId1, PointPos pos1, int geoId2, PointPos pos2, double value)
+int Sketch::addDistanceYConstraint(int geoId1, PointPos pos1, int geoId2, PointPos pos2, double * value)
 {
     geoId1 = checkGeoId(geoId1);
     geoId2 = checkGeoId(geoId2);
@@ -891,11 +1007,8 @@ int Sketch::addDistanceYConstraint(int geoId1, PointPos pos1, int geoId2, PointP
         GCS::Point &p1 = Points[pointId1];
         GCS::Point &p2 = Points[pointId2];
 
-        FixParameters.push_back(new double(value));
-        double *difference = FixParameters[FixParameters.size()-1];
-
         int tag = ++ConstraintsCounter;
-        GCSsys.addConstraintDifference(p1.y, p2.y, difference, tag);
+        GCSsys.addConstraintDifference(p1.y, p2.y, value, tag);
         return ConstraintsCounter;
     }
     return -1;
@@ -1148,7 +1261,7 @@ int Sketch::addAngleAtPointConstraint(
         int geoId1, PointPos pos1,
         int geoId2, PointPos pos2,
         int geoId3, PointPos pos3,
-        double value,
+        double * value,
         ConstraintType cTyp)
 {
 
@@ -1205,9 +1318,7 @@ int Sketch::addAngleAtPointConstraint(
         p2 = &(Points[pointId]);
     }
 
-    // add the parameter for the angle
-    FixParameters.push_back(new double(0.0));
-    double *angle = FixParameters[FixParameters.size()-1];
+    double *angle = value;
 
     //For tangency/perpendicularity, we don't just copy the angle.
     //The angle stored for tangency/perpendicularity is offset, so that the options
@@ -1215,9 +1326,8 @@ int Sketch::addAngleAtPointConstraint(
     // Use autodetect then.
     //The same functionality is implemented in SketchObject.cpp, where
     // it is used to permanently lock down the autodecision.
-    if (cTyp == Angle)
-        *angle = value;
-    else {
+    if (cTyp != Angle)
+    {
         //The same functionality is implemented in SketchObject.cpp, where
         // it is used to permanently lock down the autodecision.
         double angleOffset = 0.0;//the difference between the datum value and the actual angle to apply. (datum=angle+offset)
@@ -1225,7 +1335,7 @@ int Sketch::addAngleAtPointConstraint(
         if (cTyp == Tangent) {angleOffset = -M_PI/2; angleDesire = 0.0;}
         if (cTyp == Perpendicular) {angleOffset = 0; angleDesire = M_PI/2;}
 
-        if (value==0.0) {//autodetect tangency internal/external (and same for perpendicularity)
+        if (*value==0.0) {//autodetect tangency internal/external (and same for perpendicularity)
             double angleErr = GCSsys.calculateAngleViaPoint(*crv1, *crv2, p) - angleDesire;
             //bring angleErr to -pi..pi
             if (angleErr > M_PI) angleErr -= M_PI*2;
@@ -1237,10 +1347,9 @@ int Sketch::addAngleAtPointConstraint(
 
             *angle = angleDesire;
         } else
-            *angle = value-angleOffset;
+            *angle = *value-angleOffset;
     }
 
-
     int tag = -1;
     if(e2c)
         tag = Sketch::addPointOnObjectConstraint(geoId1, pos1, geoId2);//increases ConstraintsCounter
@@ -1256,7 +1365,7 @@ int Sketch::addAngleAtPointConstraint(
 }
 
 // line length constraint
-int Sketch::addDistanceConstraint(int geoId, double value)
+int Sketch::addDistanceConstraint(int geoId, double * value)
 {
     geoId = checkGeoId(geoId);
 
@@ -1265,31 +1374,13 @@ int Sketch::addDistanceConstraint(int geoId, double value)
 
     GCS::Line &l = Lines[Geoms[geoId].index];
 
-    // add the parameter for the length
-    FixParameters.push_back(new double(value));
-    double *distance = FixParameters[FixParameters.size()-1];
-
     int tag = ++ConstraintsCounter;
-    GCSsys.addConstraintP2PDistance(l.p1, l.p2, distance, tag);
+    GCSsys.addConstraintP2PDistance(l.p1, l.p2, value, tag);
     return ConstraintsCounter;
 }
 
-// line to line distance constraint
-int Sketch::addDistanceConstraint(int geoId1, int geoId2, double value)
-{
-    //geoId1 = checkGeoId(geoId1);
-    //geoId2 = checkGeoId(geoId2);
-
-    //assert(Geoms[geoId1].type == Line);
-    //assert(Geoms[geoId2].type == Line);
-
-    Base::Console().Warning("Line to line distance constraints are not implemented yet.\n");
-
-    return -1;
-}
-
 // point to line distance constraint
-int Sketch::addDistanceConstraint(int geoId1, PointPos pos1, int geoId2, double value)
+int Sketch::addDistanceConstraint(int geoId1, PointPos pos1, int geoId2, double * value)
 {
     geoId1 = checkGeoId(geoId1);
     geoId2 = checkGeoId(geoId2);
@@ -1303,19 +1394,15 @@ int Sketch::addDistanceConstraint(int geoId1, PointPos pos1, int geoId2, double
         GCS::Point &p1 = Points[pointId1];
         GCS::Line &l2 = Lines[Geoms[geoId2].index];
 
-        // add the parameter for the distance
-        FixParameters.push_back(new double(value));
-        double *distance = FixParameters[FixParameters.size()-1];
-
         int tag = ++ConstraintsCounter;
-        GCSsys.addConstraintP2LDistance(p1, l2, distance, tag);
+        GCSsys.addConstraintP2LDistance(p1, l2, value, tag);
         return ConstraintsCounter;
     }
     return -1;
 }
 
 // point to point distance constraint
-int Sketch::addDistanceConstraint(int geoId1, PointPos pos1, int geoId2, PointPos pos2, double value)
+int Sketch::addDistanceConstraint(int geoId1, PointPos pos1, int geoId2, PointPos pos2, double * value)
 {
     geoId1 = checkGeoId(geoId1);
     geoId2 = checkGeoId(geoId2);
@@ -1328,74 +1415,56 @@ int Sketch::addDistanceConstraint(int geoId1, PointPos pos1, int geoId2, PointPo
         GCS::Point &p1 = Points[pointId1];
         GCS::Point &p2 = Points[pointId2];
 
-        // add the parameter for the distance
-        FixParameters.push_back(new double(value));
-        double *distance = FixParameters[FixParameters.size()-1];
-
         int tag = ++ConstraintsCounter;
-        GCSsys.addConstraintP2PDistance(p1, p2, distance, tag);
+        GCSsys.addConstraintP2PDistance(p1, p2, value, tag);
         return ConstraintsCounter;
     }
     return -1;
 }
 
-int Sketch::addRadiusConstraint(int geoId, double value)
+int Sketch::addRadiusConstraint(int geoId, double * value)
 {
     geoId = checkGeoId(geoId);
 
     if (Geoms[geoId].type == Circle) {
         GCS::Circle &c = Circles[Geoms[geoId].index];
-        // add the parameter for the radius
-        FixParameters.push_back(new double(value));
-        double *radius = FixParameters[FixParameters.size()-1];
         int tag = ++ConstraintsCounter;
-        GCSsys.addConstraintCircleRadius(c, radius, tag);
+        GCSsys.addConstraintCircleRadius(c, value, tag);
         return ConstraintsCounter;
     }
     else if (Geoms[geoId].type == Arc) {
         GCS::Arc &a = Arcs[Geoms[geoId].index];
-        // add the parameter for the radius
-        FixParameters.push_back(new double(value));
-        double *radius = FixParameters[FixParameters.size()-1];
         int tag = ++ConstraintsCounter;
-        GCSsys.addConstraintArcRadius(a, radius, tag);
+        GCSsys.addConstraintArcRadius(a, value, tag);
         return ConstraintsCounter;
     }
     return -1;
 }
 
 // line orientation angle constraint
-int Sketch::addAngleConstraint(int geoId, double value)
+int Sketch::addAngleConstraint(int geoId, double * value)
 {
     geoId = checkGeoId(geoId);
 
     if (Geoms[geoId].type == Line) {
         GCS::Line &l = Lines[Geoms[geoId].index];
 
-        // add the parameter for the angle
-        FixParameters.push_back(new double(value));
-        double *angle = FixParameters[FixParameters.size()-1];
-
         int tag = ++ConstraintsCounter;
-        GCSsys.addConstraintP2PAngle(l.p1, l.p2, angle, tag);
+        GCSsys.addConstraintP2PAngle(l.p1, l.p2, value, tag);
         return ConstraintsCounter;
     }
     else if (Geoms[geoId].type == Arc) {
         GCS::Arc &a = Arcs[Geoms[geoId].index];
 
-        // add the parameter for the angle
-        FixParameters.push_back(new double(value));
-        double *angle = FixParameters[FixParameters.size()-1];
-
         int tag = ++ConstraintsCounter;
-        GCSsys.addConstraintL2LAngle(a.center, a.start, a.center, a.end, angle, tag);
+        GCSsys.addConstraintL2LAngle(a.center, a.start, a.center, a.end, value, tag);
         return ConstraintsCounter;
     }
     return -1;
 }
 
 // line to line angle constraint
-int Sketch::addAngleConstraint(int geoId1, int geoId2, double value)
+int Sketch::addAngleConstraint(int geoId1, int geoId2, double * value)
 {
     geoId1 = checkGeoId(geoId1);
     geoId2 = checkGeoId(geoId2);
@@ -1407,17 +1476,13 @@ int Sketch::addAngleConstraint(int geoId1, int geoId2, double value)
     GCS::Line &l1 = Lines[Geoms[geoId1].index];
     GCS::Line &l2 = Lines[Geoms[geoId2].index];
 
-    // add the parameter for the angle
-    FixParameters.push_back(new double(value));
-    double *angle = FixParameters[FixParameters.size()-1];
-
     int tag = ++ConstraintsCounter;
-    GCSsys.addConstraintL2LAngle(l1, l2, angle, tag);
+    GCSsys.addConstraintL2LAngle(l1, l2, value, tag);
     return ConstraintsCounter;
 }
 
 // line to line angle constraint (with explicitly given start points)
-int Sketch::addAngleConstraint(int geoId1, PointPos pos1, int geoId2, PointPos pos2, double value)
+int Sketch::addAngleConstraint(int geoId1, PointPos pos1, int geoId2, PointPos pos2, double * value)
 {
     geoId1 = checkGeoId(geoId1);
     geoId2 = checkGeoId(geoId2);
@@ -1447,12 +1512,8 @@ int Sketch::addAngleConstraint(int geoId1, PointPos pos1, int geoId2, PointPos p
     if (l1p1 == 0 || l2p1 == 0)
         return -1;
 
-    // add the parameter for the angle
-    FixParameters.push_back(new double(value));
-    double *angle = FixParameters[FixParameters.size()-1];
-
     int tag = ++ConstraintsCounter;
-    GCSsys.addConstraintL2LAngle(*l1p1, *l1p2, *l2p1, *l2p2, angle, tag);
+    GCSsys.addConstraintL2LAngle(*l1p1, *l1p2, *l2p1, *l2p2, value, tag);
     return ConstraintsCounter;
 }
 
@@ -1644,7 +1705,9 @@ int Sketch::addSymmetricConstraint(int geoId1, PointPos pos1, int geoId2, PointP
 int Sketch::addSnellsLawConstraint(int geoIdRay1, PointPos posRay1,
                                    int geoIdRay2, PointPos posRay2,
                                    int geoIdBnd,
-                                   double n2divn1)
+                                   double * value, 
+                                   double * secondvalue
+                                  )
 {
 
     geoIdRay1 = checkGeoId(geoIdRay1);
@@ -1675,12 +1738,13 @@ int Sketch::addSnellsLawConstraint(int geoIdRay1, PointPos posRay1,
     GCS::Point &p1 = Points[pointId1];
     GCS::Point &p2 = Points[pointId2];
 
-    // add the parameters (refractive indexes)
-    FixParameters.push_back(new double(0.0));
-    double *n1 = FixParameters[FixParameters.size()-1];
-    FixParameters.push_back(new double(0.0));
-    double *n2 = FixParameters[FixParameters.size()-1];
-
+    // add the parameters (refractive indexes)   
+    // n1 uses the place hold by n2divn1, so that is retrivable in updateNonDrivingConstraints
+    double *n1 = value;
+    double *n2 = secondvalue;
+    
+    double n2divn1=*value;
+    
     if ( abs(n2divn1) >= 1.0 ){
         *n2 = n2divn1;
         *n1 = 1.0;
@@ -1993,6 +2057,23 @@ bool Sketch::updateGeometry()
     return true;
 }
 
+bool Sketch::updateNonDrivingConstraints()
+{    
+     for (std::vector<ConstrDef>::iterator it = Constrs.begin();it!=Constrs.end();++it){
+        if(!(*it).driving) {
+            if((*it).constr->Type==SnellsLaw) {
+                double n1 = *((*it).value);
+                double n2 = *((*it).secondvalue);
+                
+                (*it).constr->Value = n2/n1;
+            }
+            else
+                (*it).constr->Value=*((*it).value);
+        }
+     }
+    return true;
+}
+
 // solving ==========================================================
 
 int Sketch::solve(void)
@@ -2043,6 +2124,9 @@ int Sketch::solve(void)
                 GCSsys.undoSolution();
                 updateGeometry();
                 Base::Console().Warning("Invalid solution from %s solver.\n", solvername.c_str());
+            }else
+            {
+                updateNonDrivingConstraints();
             }
         } else {
             valid_solution = false;
diff --git a/src/Mod/Sketcher/App/Sketch.h b/src/Mod/Sketcher/App/Sketch.h
index dd91aa075e..fff2e63dc2 100644
--- a/src/Mod/Sketcher/App/Sketch.h
+++ b/src/Mod/Sketcher/App/Sketch.h
@@ -135,14 +135,14 @@ public:
     /// add one constraint to the sketch
     int addConstraint(const Constraint *constraint);
     /// add a fixed coordinate constraint to a point
-    int addCoordinateXConstraint(int geoId, PointPos pos, double value);
-    int addCoordinateYConstraint(int geoId, PointPos pos, double value);
+    int addCoordinateXConstraint(int geoId, PointPos pos, double * value);
+    int addCoordinateYConstraint(int geoId, PointPos pos, double *  value);
     /// add a horizontal distance constraint to two points or line ends
-    int addDistanceXConstraint(int geoId, double value);
-    int addDistanceXConstraint(int geoId1, PointPos pos1, int geoId2, PointPos pos2, double value);
+    int addDistanceXConstraint(int geoId, double * value);
+    int addDistanceXConstraint(int geoId1, PointPos pos1, int geoId2, PointPos pos2, double * value);
     /// add a vertical distance constraint to two points or line ends
-    int addDistanceYConstraint(int geoId, double value);
-    int addDistanceYConstraint(int geoId1, PointPos pos1, int geoId2, PointPos pos2, double value);
+    int addDistanceYConstraint(int geoId, double *  value);
+    int addDistanceYConstraint(int geoId1, PointPos pos1, int geoId2, PointPos pos2, double *  value);
     /// add a horizontal constraint to a geometry
     int addHorizontalConstraint(int geoId);
     int addHorizontalConstraint(int geoId1, PointPos pos1, int geoId2, PointPos pos2);
@@ -152,10 +152,9 @@ public:
     /// add a coincident constraint to two points of two geometries
     int addPointCoincidentConstraint(int geoId1, PointPos pos1, int geoId2, PointPos pos2);
     /// add a length or distance constraint
-    int addDistanceConstraint(int geoId1, double value);
-    int addDistanceConstraint(int geoId1, int geoId2, double value);
-    int addDistanceConstraint(int geoId1, PointPos pos1, int geoId2, double value);
-    int addDistanceConstraint(int geoId1, PointPos pos1, int geoId2, PointPos pos2, double value);
+    int addDistanceConstraint(int geoId1, double *  value);
+    int addDistanceConstraint(int geoId1, PointPos pos1, int geoId2, double *  value);
+    int addDistanceConstraint(int geoId1, PointPos pos1, int geoId2, PointPos pos2, double *  value);
     /// add a parallel constraint between two lines
     int addParallelConstraint(int geoId1, int geoId2);
     /// add a perpendicular constraint between two lines
@@ -166,14 +165,14 @@ public:
             int geoId1, PointPos pos1,
             int geoId2, PointPos pos2,
             int geoId3, PointPos pos3,
-            double value,
+            double *  value,
             ConstraintType cTyp);
     /// add a radius constraint on a circle or an arc
-    int addRadiusConstraint(int geoId, double value);
+    int addRadiusConstraint(int geoId, double *  value);
     /// add an angle constraint on a line or between two lines
-    int addAngleConstraint(int geoId, double value);
-    int addAngleConstraint(int geoId1, int geoId2, double value);
-    int addAngleConstraint(int geoId1, PointPos pos1, int geoId2, PointPos pos2, double value);
+    int addAngleConstraint(int geoId, double *  value);
+    int addAngleConstraint(int geoId1, int geoId2, double *  value);
+    int addAngleConstraint(int geoId1, PointPos pos1, int geoId2, PointPos pos2, double *  value);
     /// add angle-via-point constraint between any two curves
     int addAngleViaPointConstraint(int geoId1, int geoId2, int geoId3, PointPos pos3, double value);
     /// add an equal length or radius constraints between two lines or between circles and arcs
@@ -188,7 +187,8 @@ public:
     int addSnellsLawConstraint(int geoIdRay1, PointPos posRay1,
                                int geoIdRay2, PointPos posRay2,
                                int geoIdBnd,
-                               double n2divn1);
+                               double *  value,
+                               double *  second);
     //@}
     
     /// Internal Alignment constraints
@@ -238,8 +238,17 @@ protected:
         int               midPointId;      // index in Points of the start point of this geometry
         int               endPointId;      // index in Points of the end point of this geometry
     };
+    
+    struct ConstrDef {
+        ConstrDef() : driving(true) {}
+        Constraint *    constr;             // pointer to the constraint
+        bool            driving;
+        double *        value;
+        double *        secondvalue;        // this is needed for SnellsLaw
+    };
 
     std::vector<GeoDef> Geoms;
+    std::vector<ConstrDef> Constrs;
     GCS::System GCSsys;
     int ConstraintsCounter;
     std::vector<int> Conflicting;
@@ -264,6 +273,7 @@ protected:
 private:
 
     bool updateGeometry(void);
+    bool updateNonDrivingConstraints(void);
 
     /// checks if the index bounds and converts negative indices to positive
     int checkGeoId(int geoId);
diff --git a/src/Mod/Sketcher/App/SketchObject.cpp b/src/Mod/Sketcher/App/SketchObject.cpp
index 35f6fa0bc7..2e5d017466 100644
--- a/src/Mod/Sketcher/App/SketchObject.cpp
+++ b/src/Mod/Sketcher/App/SketchObject.cpp
@@ -219,6 +219,60 @@ int SketchObject::setDatum(int ConstrId, double Datum)
     return err;
 }
 
+int SketchObject::setDriving(int ConstrId, bool isdriving)
+{
+    const std::vector<Constraint *> &vals = this->Constraints.getValues();
+    
+    if (ConstrId < 0 || ConstrId >= int(vals.size()))
+        return -1;
+    
+    ConstraintType type = vals[ConstrId]->Type;
+    
+    if (type != Distance &&
+        type != DistanceX &&
+        type != DistanceY &&
+        type != Radius &&
+        type != Angle &&
+        type != SnellsLaw)
+        return -1;
+
+    // copy the list
+    std::vector<Constraint *> newVals(vals);
+    // clone the changed Constraint
+    Constraint *constNew = vals[ConstrId]->clone();
+    constNew->isDriving = isdriving;
+    newVals[ConstrId] = constNew;
+    this->Constraints.setValues(newVals);
+    delete constNew;
+
+    int err = solve();
+    if (err)
+        this->Constraints.setValues(vals);
+
+    return err;
+}
+
+int SketchObject::getDriving(int ConstrId, bool &isdriving)
+{
+    const std::vector<Constraint *> &vals = this->Constraints.getValues();
+    
+    if (ConstrId < 0 || ConstrId >= int(vals.size()))
+        return -1;
+    
+    ConstraintType type = vals[ConstrId]->Type;
+    
+    if (type != Distance &&
+        type != DistanceX &&
+        type != DistanceY &&
+        type != Radius &&
+        type != Angle &&
+        type != SnellsLaw)
+        return -1;
+
+    isdriving=vals[ConstrId]->isDriving;
+    return 0;
+}
+
 int SketchObject::movePoint(int GeoId, PointPos PosId, const Base::Vector3d& toPoint, bool relative)
 {
     Sketch sketch;
diff --git a/src/Mod/Sketcher/App/SketchObject.h b/src/Mod/Sketcher/App/SketchObject.h
index 6ac6207f54..0be407c5e0 100644
--- a/src/Mod/Sketcher/App/SketchObject.h
+++ b/src/Mod/Sketcher/App/SketchObject.h
@@ -110,6 +110,10 @@ public:
     int solve();
     /// set the datum of a Distance or Angle constraint and solve
     int setDatum(int ConstrId, double Datum);
+    /// set the driving status of this constraint and solve
+    int setDriving(int ConstrId, bool isdriving);
+    /// get the driving status of this constraint
+    int getDriving(int ConstrId, bool &isdriving);
     /// move this point to a new location and solve
     int movePoint(int GeoId, PointPos PosId, const Base::Vector3d& toPoint, bool relative=false);
     /// retrieves the coordinates of a point
diff --git a/src/Mod/Sketcher/App/SketchObjectPy.xml b/src/Mod/Sketcher/App/SketchObjectPy.xml
index 933ec00463..ccc48516d0 100644
--- a/src/Mod/Sketcher/App/SketchObjectPy.xml
+++ b/src/Mod/Sketcher/App/SketchObjectPy.xml
@@ -78,6 +78,16 @@
         <UserDocu>Get the value of a datum constraint</UserDocu>
       </Documentation>
     </Methode>
+    <Methode Name="setDriving">
+      <Documentation>
+        <UserDocu>set the Driving status of a datum constraint</UserDocu>
+      </Documentation>
+    </Methode>
+    <Methode Name="getDriving">
+      <Documentation>
+        <UserDocu>Get the Driving status of a datum constraint</UserDocu>
+      </Documentation>
+    </Methode>    
     <Methode Name="movePoint">
       <Documentation>
         <UserDocu>
diff --git a/src/Mod/Sketcher/App/SketchObjectPyImp.cpp b/src/Mod/Sketcher/App/SketchObjectPyImp.cpp
index 943380d997..62fe6738f6 100644
--- a/src/Mod/Sketcher/App/SketchObjectPyImp.cpp
+++ b/src/Mod/Sketcher/App/SketchObjectPyImp.cpp
@@ -568,6 +568,42 @@ PyObject* SketchObjectPy::getDatum(PyObject *args)
     return new Base::QuantityPy(new Base::Quantity(datum));
 }
 
+PyObject* SketchObjectPy::setDriving(PyObject *args)
+{
+    PyObject* driving;
+    int constrid;
+    
+    if (!PyArg_ParseTuple(args, "iO!", &constrid, &PyBool_Type, &driving))
+        return 0;
+
+    if (this->getSketchObjectPtr()->setDriving(constrid, PyObject_IsTrue(driving) ? true : false)) {
+        std::stringstream str;
+        str << "Not able set Driving for constraint with the given index: " << constrid;
+        PyErr_SetString(PyExc_ValueError, str.str().c_str());
+        return 0;
+    }
+
+    Py_Return;
+}
+
+PyObject* SketchObjectPy::getDriving(PyObject *args)
+{
+    int constrid;
+    bool driving;
+    
+    if (!PyArg_ParseTuple(args, "i", &constrid))
+        return 0;
+
+    SketchObject* obj = this->getSketchObjectPtr();
+    if (this->getSketchObjectPtr()->getDriving(constrid, driving)) {
+        PyErr_SetString(PyExc_ValueError, "Invalid constraint id");
+        return 0;
+    }
+
+    return Py::new_reference_to(Py::Boolean(driving));
+}
+
+
 PyObject* SketchObjectPy::movePoint(PyObject *args)
 {
     PyObject *pcObj;
diff --git a/src/Mod/Sketcher/Gui/CommandConstraints.cpp b/src/Mod/Sketcher/Gui/CommandConstraints.cpp
index 4534260f4a..f2c9ab670c 100644
--- a/src/Mod/Sketcher/Gui/CommandConstraints.cpp
+++ b/src/Mod/Sketcher/Gui/CommandConstraints.cpp
@@ -158,7 +158,7 @@ void openEditDatumDialog(Sketcher::SketchObject* sketch, int ConstrNbr)
 }
 
 // Utility method to avoid repeating the same code over and over again
-void finishDistanceConstraint(Gui::Command* cmd, Sketcher::SketchObject* sketch)
+void finishDistanceConstraint(Gui::Command* cmd, Sketcher::SketchObject* sketch, bool isDriven=true)
 {
     // Get the latest constraint
     const std::vector<Sketcher::Constraint *> &ConStr = sketch->Constraints.getValues();
@@ -179,11 +179,11 @@ void finishDistanceConstraint(Gui::Command* cmd, Sketcher::SketchObject* sketch)
     bool show = hGrp->GetBool("ShowDialogOnDistanceConstraint", true);
 
     // Ask for the value of the distance immediately
-    if (show) {
+    if (show && isDriven) {
         openEditDatumDialog(sketch, ConStr.size() - 1);
     }
     else {
-        // now dialog was shown so commit the command
+        // no dialog was shown so commit the command
         cmd->commitCommand();
     }
 
@@ -191,17 +191,18 @@ void finishDistanceConstraint(Gui::Command* cmd, Sketcher::SketchObject* sketch)
     cmd->getSelection().clearSelection();
 }
 
+void showNoConstraintBetweenExternal()
+{
+        QMessageBox::warning(Gui::getMainWindow(), QObject::tr("Wrong selection"),
+                             QObject::tr("Cannot add a constraint between two external geometries!"));    
+}
+
 bool checkBothExternal(int GeoId1, int GeoId2)
 {
     if (GeoId1 == Constraint::GeoUndef || GeoId2 == Constraint::GeoUndef)
         return false;
-    else if (GeoId1 < 0 && GeoId2 < 0) {
-        QMessageBox::warning(Gui::getMainWindow(), QObject::tr("Wrong selection"),
-                             QObject::tr("Cannot add a constraint between two external geometries!"));
-        return true;
-    }
     else
-        return false;
+        return (GeoId1 < 0 && GeoId2 < 0);
 }
 
 void getIdsFromName(const std::string &name, const Sketcher::SketchObject* Obj,
@@ -711,9 +712,9 @@ void CmdSketcherConstrainLock::activated(int iMsg)
     Sketcher::PointPos PosId;
     getIdsFromName(SubNames[0], Obj, GeoId, PosId);
 
-    if (isEdge(GeoId,PosId) || GeoId < 0) {
+    if (isEdge(GeoId,PosId) || (GeoId < 0 && GeoId >= -2)) {
         QMessageBox::warning(Gui::getMainWindow(), QObject::tr("Wrong selection"),
-            QObject::tr("Select one vertex from the sketch."));
+            QObject::tr("Select one vertex from the sketch other than the origin."));
         return;
     }
 
@@ -728,6 +729,16 @@ void CmdSketcherConstrainLock::activated(int iMsg)
         Doc,"App.ActiveDocument.%s.addConstraint(Sketcher.Constraint('DistanceY',%d,%d,%f)) ",
         selection[0].getFeatName(),GeoId,PosId,pnt.y);
 
+    if (GeoId < -2) { // it is a constraint on a external line, make it non-driving
+        const std::vector<Sketcher::Constraint *> &ConStr = Obj->Constraints.getValues();
+        
+        Gui::Command::doCommand(Doc,"App.ActiveDocument.%s.setDriving(%i,%s)",
+        selection[0].getFeatName(),ConStr.size()-2,"False");
+        
+        Gui::Command::doCommand(Doc,"App.ActiveDocument.%s.setDriving(%i,%s)",
+        selection[0].getFeatName(),ConStr.size()-1,"False");
+    }
+    
     // finish the transaction and update
     commitCommand();
     updateActive();
@@ -885,10 +896,10 @@ void CmdSketcherConstrainDistance::activated(int iMsg)
     getIdsFromName(SubNames[0], Obj, GeoId1, PosId1);
     if (SubNames.size() == 2)
         getIdsFromName(SubNames[1], Obj, GeoId2, PosId2);
-
-    if (checkBothExternal(GeoId1, GeoId2))
-        return;
-    else if (isVertex(GeoId1,PosId1) && (GeoId2 == -2 || GeoId2 == -1)) {
+    
+    bool bothexternal=checkBothExternal(GeoId1, GeoId2);
+    
+    if (isVertex(GeoId1,PosId1) && (GeoId2 == -2 || GeoId2 == -1)) {
         std::swap(GeoId1,GeoId2);
         std::swap(PosId1,PosId2);
     }
@@ -920,8 +931,16 @@ void CmdSketcherConstrainDistance::activated(int iMsg)
                 Doc,"App.ActiveDocument.%s.addConstraint(Sketcher.Constraint('Distance',%d,%d,%d,%d,%f)) ",
                 selection[0].getFeatName(),GeoId1,PosId1,GeoId2,PosId2,(pnt2-pnt1).Length());
         }
-
-        finishDistanceConstraint(this, Obj);
+        
+        if (bothexternal) { // it is a constraint on a external line, make it non-driving
+            const std::vector<Sketcher::Constraint *> &ConStr = Obj->Constraints.getValues();
+            
+            Gui::Command::doCommand(Doc,"App.ActiveDocument.%s.setDriving(%i,%s)",
+            selection[0].getFeatName(),ConStr.size()-1,"False");
+            finishDistanceConstraint(this, Obj,false);
+        }
+        else
+            finishDistanceConstraint(this, Obj,true);
         return;
     }
     else if ((isVertex(GeoId1,PosId1) && isEdge(GeoId2,PosId2)) ||
@@ -945,15 +964,23 @@ void CmdSketcherConstrainDistance::activated(int iMsg)
                 Doc,"App.ActiveDocument.%s.addConstraint(Sketcher.Constraint('Distance',%d,%d,%d,%f)) ",
                 selection[0].getFeatName(),GeoId1,PosId1,GeoId2,ActDist);
 
-            finishDistanceConstraint(this, Obj);
+            if (bothexternal) { // it is a constraint on a external line, make it non-driving
+                const std::vector<Sketcher::Constraint *> &ConStr = Obj->Constraints.getValues();
+                
+                Gui::Command::doCommand(Doc,"App.ActiveDocument.%s.setDriving(%i,%s)",
+                selection[0].getFeatName(),ConStr.size()-1,"False");
+                finishDistanceConstraint(this, Obj,false);
+            }
+            else
+                finishDistanceConstraint(this, Obj,true);
+            
             return;
         }
     }
     else if (isEdge(GeoId1,PosId1)) { // line length
-        if (GeoId1 < 0) {
+        if (GeoId1 < 0 && GeoId1 >= -2) {
             QMessageBox::warning(Gui::getMainWindow(), QObject::tr("Wrong selection"),
-                                 GeoId1 < 2 ? QObject::tr("Cannot add a length constraint on an external geometry!")
-                                            : QObject::tr("Cannot add a length constraint on an axis!"));
+                                 QObject::tr("Cannot add a length constraint on an axis!"));
             return;
         }
 
@@ -967,8 +994,17 @@ void CmdSketcherConstrainDistance::activated(int iMsg)
             Gui::Command::doCommand(
                 Doc,"App.ActiveDocument.%s.addConstraint(Sketcher.Constraint('Distance',%d,%f)) ",
                 selection[0].getFeatName(),GeoId1,ActLength);
-
-            finishDistanceConstraint(this, Obj);
+            
+            if (GeoId1 < -2) { // it is a constraint on a external line, make it non-driving
+                const std::vector<Sketcher::Constraint *> &ConStr = Obj->Constraints.getValues();
+                
+                Gui::Command::doCommand(Doc,"App.ActiveDocument.%s.setDriving(%i,%s)",
+                selection[0].getFeatName(),ConStr.size()-1,"False");
+                finishDistanceConstraint(this, Obj,false);
+            }
+            else
+                finishDistanceConstraint(this, Obj,true);
+            
             return;
         }
     }
@@ -1035,8 +1071,10 @@ void CmdSketcherConstrainPointOnObject::activated(int iMsg)
         int cnt = 0;
         for (int iPnt = 0;  iPnt < points.size();  iPnt++) {
             for (int iCrv = 0;  iCrv < curves.size();  iCrv++) {
-                if (checkBothExternal(points[iPnt].GeoId, curves[iCrv].GeoId))
+                if (checkBothExternal(points[iPnt].GeoId, curves[iCrv].GeoId)){
+                    showNoConstraintBetweenExternal();
                     continue;
+                }
                 if (points[iPnt].GeoId == curves[iCrv].GeoId)
                     continue; //constraining a point of an element onto the element is a bad idea...
                 cnt++;
@@ -1112,9 +1150,9 @@ void CmdSketcherConstrainDistanceX::activated(int iMsg)
     if (SubNames.size() == 2)
         getIdsFromName(SubNames[1], Obj, GeoId2, PosId2);
 
-    if (checkBothExternal(GeoId1, GeoId2))
-        return;
-    else if (GeoId2 == -1 || GeoId2 == -2) {
+    bool bothexternal=checkBothExternal(GeoId1, GeoId2);
+
+    if (GeoId2 == -1 || GeoId2 == -2) {
         std::swap(GeoId1,GeoId2);
         std::swap(PosId1,PosId2);
     }
@@ -1137,15 +1175,23 @@ void CmdSketcherConstrainDistanceX::activated(int iMsg)
             Doc,"App.ActiveDocument.%s.addConstraint(Sketcher.Constraint('DistanceX',%d,%d,%d,%d,%f)) ",
             selection[0].getFeatName(),GeoId1,PosId1,GeoId2,PosId2,ActLength);
 
-        finishDistanceConstraint(this, Obj);
+        if (bothexternal) { // it is a constraint on a external line, make it non-driving
+            const std::vector<Sketcher::Constraint *> &ConStr = Obj->Constraints.getValues();
+            
+            Gui::Command::doCommand(Doc,"App.ActiveDocument.%s.setDriving(%i,%s)",
+            selection[0].getFeatName(),ConStr.size()-1,"False");
+            finishDistanceConstraint(this, Obj,false);
+        }
+        else
+            finishDistanceConstraint(this, Obj,true);
+
         return;
     }
     else if (isEdge(GeoId1,PosId1) && GeoId2 == Constraint::GeoUndef)  { // horizontal length of a line
 
-        if (GeoId1 < 0) {
+        if (GeoId1 < 0 && GeoId1 >= -2) {
             QMessageBox::warning(Gui::getMainWindow(), QObject::tr("Wrong selection"),
-                GeoId1 < -2 ? QObject::tr("Cannot add a horizontal length constraint on an external geometry!")
-                            : QObject::tr("Cannot add a horizontal length constraint on an axis!"));
+                            QObject::tr("Cannot add a horizontal length constraint on an axis!"));
             return;
         }
 
@@ -1160,16 +1206,24 @@ void CmdSketcherConstrainDistanceX::activated(int iMsg)
                 Doc,"App.ActiveDocument.%s.addConstraint(Sketcher.Constraint('DistanceX',%d,%f)) ",
                 selection[0].getFeatName(),GeoId1,ActLength);
 
-            finishDistanceConstraint(this, Obj);
+            if (GeoId1 < -2) { // it is a constraint on a external line, make it non-driving
+                const std::vector<Sketcher::Constraint *> &ConStr = Obj->Constraints.getValues();
+                
+                Gui::Command::doCommand(Doc,"App.ActiveDocument.%s.setDriving(%i,%s)",
+                selection[0].getFeatName(),ConStr.size()-1,"False");
+                finishDistanceConstraint(this, Obj,false);
+            }
+            else
+                finishDistanceConstraint(this, Obj,true);
+            
             return;
         }
     }
     else if (isVertex(GeoId1,PosId1) && GeoId2 == Constraint::GeoUndef) { // point on fixed x-coordinate
 
-        if (GeoId1 < 0) {
+        if (GeoId1 < 0 && GeoId1 >= -2) {
             QMessageBox::warning(Gui::getMainWindow(), QObject::tr("Wrong selection"),
-                GeoId1 < -2 ? QObject::tr("Cannot add a fixed x-coordinate constraint on an external geometry!")
-                            : QObject::tr("Cannot add a fixed x-coordinate constraint on the root point!"));
+                    QObject::tr("Cannot add a fixed x-coordinate constraint on the root point!"));
             return;
         }
 
@@ -1180,8 +1234,17 @@ void CmdSketcherConstrainDistanceX::activated(int iMsg)
         Gui::Command::doCommand(
             Doc,"App.ActiveDocument.%s.addConstraint(Sketcher.Constraint('DistanceX',%d,%d,%f)) ",
             selection[0].getFeatName(),GeoId1,PosId1,ActX);
-
-        finishDistanceConstraint(this, Obj);
+        
+        if (GeoId1 < -2) { // it is a constraint on a external line, make it non-driving
+            const std::vector<Sketcher::Constraint *> &ConStr = Obj->Constraints.getValues();
+            
+            Gui::Command::doCommand(Doc,"App.ActiveDocument.%s.setDriving(%i,%s)",
+            selection[0].getFeatName(),ConStr.size()-1,"False");
+            finishDistanceConstraint(this, Obj,false);
+        }
+        else
+            finishDistanceConstraint(this, Obj,true);
+            
         return;
     }
 
@@ -1240,9 +1303,9 @@ void CmdSketcherConstrainDistanceY::activated(int iMsg)
     if (SubNames.size() == 2)
         getIdsFromName(SubNames[1], Obj, GeoId2, PosId2);
 
-    if (checkBothExternal(GeoId1, GeoId2))
-        return;
-    else if (GeoId2 == -1 || GeoId2 == -2) {
+    bool bothexternal=checkBothExternal(GeoId1, GeoId2);
+    
+    if (GeoId2 == -1 || GeoId2 == -2) {
         std::swap(GeoId1,GeoId2);
         std::swap(PosId1,PosId2);
     }
@@ -1263,15 +1326,23 @@ void CmdSketcherConstrainDistanceY::activated(int iMsg)
             Doc,"App.ActiveDocument.%s.addConstraint(Sketcher.Constraint('DistanceY',%d,%d,%d,%d,%f)) ",
             selection[0].getFeatName(),GeoId1,PosId1,GeoId2,PosId2,ActLength);
 
-        finishDistanceConstraint(this, Obj);
+        if (bothexternal) { // it is a constraint on a external line, make it non-driving
+            const std::vector<Sketcher::Constraint *> &ConStr = Obj->Constraints.getValues();
+            
+            Gui::Command::doCommand(Doc,"App.ActiveDocument.%s.setDriving(%i,%s)",
+            selection[0].getFeatName(),ConStr.size()-1,"False");
+            finishDistanceConstraint(this, Obj,false);
+        }
+        else
+            finishDistanceConstraint(this, Obj,true);
+        
         return;
     }
     else if (isEdge(GeoId1,PosId1) && GeoId2 == Constraint::GeoUndef)  { // vertical length of a line
 
-        if (GeoId1 < 0) {
+        if (GeoId1 < 0 && GeoId1 >= -2) {
             QMessageBox::warning(Gui::getMainWindow(), QObject::tr("Wrong selection"),
-                GeoId1 < -2 ? QObject::tr("Cannot add a vertical length constraint on an external geometry!")
-                            : QObject::tr("Cannot add a vertical length constraint on an axis!"));
+                        QObject::tr("Cannot add a vertical length constraint on an axis!"));
             return;
         }
 
@@ -1286,16 +1357,24 @@ void CmdSketcherConstrainDistanceY::activated(int iMsg)
                 Doc,"App.ActiveDocument.%s.addConstraint(Sketcher.Constraint('DistanceY',%d,%f)) ",
                 selection[0].getFeatName(),GeoId1,ActLength);
 
-            finishDistanceConstraint(this, Obj);
+            if (GeoId1 < -2) { // it is a constraint on a external line, make it non-driving
+                const std::vector<Sketcher::Constraint *> &ConStr = Obj->Constraints.getValues();
+                
+                Gui::Command::doCommand(Doc,"App.ActiveDocument.%s.setDriving(%i,%s)",
+                selection[0].getFeatName(),ConStr.size()-1,"False");
+                finishDistanceConstraint(this, Obj,false);
+            }
+            else
+                finishDistanceConstraint(this, Obj,true);
+            
             return;
         }
     }
     else if (isVertex(GeoId1,PosId1) && GeoId2 == Constraint::GeoUndef) { // point on fixed y-coordinate
 
-        if (GeoId1 < 0) {
+        if (GeoId1 < 0 && GeoId1 >= -2) {
             QMessageBox::warning(Gui::getMainWindow(), QObject::tr("Wrong selection"),
-                GeoId1 < -2 ? QObject::tr("Cannot add a fixed y-coordinate constraint on an external geometry!")
-                            : QObject::tr("Cannot add a fixed y-coordinate constraint on the root point!"));
+                QObject::tr("Cannot add a fixed y-coordinate constraint on the root point!"));
             return;
         }
 
@@ -1307,7 +1386,16 @@ void CmdSketcherConstrainDistanceY::activated(int iMsg)
             Doc,"App.ActiveDocument.%s.addConstraint(Sketcher.Constraint('DistanceY',%d,%d,%f)) ",
             selection[0].getFeatName(),GeoId1,PosId1,ActY);
 
-        finishDistanceConstraint(this, Obj);
+        if (GeoId1 < -2) { // it is a constraint on a external line, make it non-driving
+            const std::vector<Sketcher::Constraint *> &ConStr = Obj->Constraints.getValues();
+            
+            Gui::Command::doCommand(Doc,"App.ActiveDocument.%s.setDriving(%i,%s)",
+            selection[0].getFeatName(),ConStr.size()-1,"False");
+            finishDistanceConstraint(this, Obj,false);
+        }
+        else
+            finishDistanceConstraint(this, Obj,true);
+        
         return;
     }
 
@@ -1377,7 +1465,7 @@ void CmdSketcherConstrainParallel::activated(int iMsg)
         }
         else if (GeoId < 0) {
             if (hasAlreadyExternal) {
-                checkBothExternal(-1,-2); // just for printing the error message
+                showNoConstraintBetweenExternal();
                 return;
             }
             else
@@ -1469,8 +1557,10 @@ void CmdSketcherConstrainPerpendicular::activated(int iMsg)
     getIdsFromName(SubNames[0], Obj, GeoId1, PosId1);
     getIdsFromName(SubNames[1], Obj, GeoId2, PosId2);
 
-    if (checkBothExternal(GeoId1, GeoId2)) //checkBothExternal displays error message
+    if (checkBothExternal(GeoId1, GeoId2)){ //checkBothExternal displays error message
+        showNoConstraintBetweenExternal();
         return;
+    }
 
     if (SubNames.size() == 3) { //perpendicular via point
         getIdsFromName(SubNames[2], Obj, GeoId3, PosId3);
@@ -1740,8 +1830,10 @@ void CmdSketcherConstrainTangent::activated(int iMsg)
     getIdsFromName(SubNames[0], Obj, GeoId1, PosId1);
     getIdsFromName(SubNames[1], Obj, GeoId2, PosId2);
 
-    if (checkBothExternal(GeoId1, GeoId2)) //checkBothExternal displays error message
+    if (checkBothExternal(GeoId1, GeoId2)){ //checkBothExternal displays error message
+        showNoConstraintBetweenExternal();
         return;
+    }
     if (SubNames.size() == 3) { //tangent via point
         getIdsFromName(SubNames[2], Obj, GeoId3, PosId3);
         //let's sink the point to be GeoId3. We want to keep the order the two curves have been selected in.
@@ -1957,6 +2049,8 @@ void CmdSketcherConstrainRadius::activated(int iMsg)
 
     // check for which selected geometry the constraint can be applied
     std::vector< std::pair<int, double> > geoIdRadiusMap;
+    std::vector< std::pair<int, double> > externalGeoIdRadiusMap;
+    
     for (std::vector<std::string>::const_iterator it = SubNames.begin(); it != SubNames.end(); ++it) {
         if (it->size() > 4 && it->substr(0,4) == "Edge") {
             int GeoId = std::atoi(it->substr(4,4000).c_str()) - 1;
@@ -1972,13 +2066,74 @@ void CmdSketcherConstrainRadius::activated(int iMsg)
                 geoIdRadiusMap.push_back(std::make_pair(GeoId, radius));
             }
         }
+        if (it->size() > 4 && it->substr(0,12) == "ExternalEdge") {
+            int GeoId = -std::atoi(it->substr(12,4000).c_str()) - 2;
+            const Part::Geometry *geom = Obj->getGeometry(GeoId);
+            if (geom && geom->getTypeId() == Part::GeomArcOfCircle::getClassTypeId()) {
+                const Part::GeomArcOfCircle *arc = dynamic_cast<const Part::GeomArcOfCircle *>(geom);
+                double radius = arc->getRadius();
+                externalGeoIdRadiusMap.push_back(std::make_pair(GeoId, radius));
+            }
+            else if (geom && geom->getTypeId() == Part::GeomCircle::getClassTypeId()) { 
+                const Part::GeomCircle *circle = dynamic_cast<const Part::GeomCircle *>(geom);
+                double radius = circle->getRadius();
+                externalGeoIdRadiusMap.push_back(std::make_pair(GeoId, radius));
+            }
+        }
     }
 
-    if (geoIdRadiusMap.empty()) {
+    if (geoIdRadiusMap.empty() && externalGeoIdRadiusMap.empty()) {
         QMessageBox::warning(Gui::getMainWindow(), QObject::tr("Wrong selection"),
             QObject::tr("Select one or more arcs or circles from the sketch."));
     }
-    else {
+    
+    bool commitNeeded=false;
+    bool updateNeeded=false;
+    bool commandopened=false;
+    
+    if(!externalGeoIdRadiusMap.empty()) {
+        // Create the non-driving radius constraints now
+        openCommand("Add radius constraint");
+        commandopened=true;
+        unsigned int constrSize;
+        
+        for (std::vector< std::pair<int, double> >::iterator it = externalGeoIdRadiusMap.begin(); it != externalGeoIdRadiusMap.end(); ++it) {
+            Gui::Command::doCommand(
+                Doc,"App.ActiveDocument.%s.addConstraint(Sketcher.Constraint('Radius',%d,%f)) ",
+                selection[0].getFeatName(),it->first,it->second);
+
+            const std::vector<Sketcher::Constraint *> &ConStr = Obj->Constraints.getValues();
+            
+            constrSize=ConStr.size();
+            
+            Gui::Command::doCommand(Doc,"App.ActiveDocument.%s.setDriving(%i,%s)",
+            selection[0].getFeatName(),constrSize-1,"False");            
+        }
+        
+        const std::vector<Sketcher::Constraint *> &ConStr = Obj->Constraints.getValues();
+        
+        std::size_t indexConstr = constrSize - externalGeoIdRadiusMap.size();
+
+        // Guess some reasonable distance for placing the datum text
+        Gui::Document *doc = getActiveGuiDocument();
+        float sf = 1.f;
+        if (doc && doc->getInEdit() && doc->getInEdit()->isDerivedFrom(SketcherGui::ViewProviderSketch::getClassTypeId())) {
+            SketcherGui::ViewProviderSketch *vp = dynamic_cast<SketcherGui::ViewProviderSketch*>(doc->getInEdit());
+            sf = vp->getScaleFactor();
+
+            for (std::size_t i=0; i<externalGeoIdRadiusMap.size();i++) {
+                Sketcher::Constraint *constr = ConStr[indexConstr + i];
+                constr->LabelDistance = 2. * sf;
+            }
+            vp->draw(); // Redraw
+        }
+        
+        commitNeeded=true;
+        updateNeeded=true;
+    }
+    
+    if(!geoIdRadiusMap.empty())
+    {
         bool constrainEqual = false;
         if (geoIdRadiusMap.size() > 1) {
             int ret = QMessageBox::question(Gui::getMainWindow(), QObject::tr("Constrain equal"),
@@ -1998,7 +2153,10 @@ void CmdSketcherConstrainRadius::activated(int iMsg)
             // Create the one radius constraint now
             int refGeoId = geoIdRadiusMap.front().first;
             double radius = geoIdRadiusMap.front().second;
-            openCommand("Add radius constraint");
+            
+            if(!commandopened)
+                openCommand("Add radius constraint");
+            
             Gui::Command::doCommand(
                 Doc,"App.ActiveDocument.%s.addConstraint(Sketcher.Constraint('Radius',%d,%f)) ",
                 selection[0].getFeatName(),refGeoId,radius);
@@ -2012,7 +2170,8 @@ void CmdSketcherConstrainRadius::activated(int iMsg)
         }
         else {
             // Create the radius constraints now
-            openCommand("Add radius constraint");
+            if(!commandopened)
+                openCommand("Add radius constraint");
             for (std::vector< std::pair<int, double> >::iterator it = geoIdRadiusMap.begin(); it != geoIdRadiusMap.end(); ++it) {
                 Gui::Command::doCommand(
                     Doc,"App.ActiveDocument.%s.addConstraint(Sketcher.Constraint('Radius',%d,%f)) ",
@@ -2072,6 +2231,8 @@ void CmdSketcherConstrainRadius::activated(int iMsg)
                     }
                     commitCommand();
                     updateActive();
+                    commitNeeded=false;
+                    updateNeeded=false;
                 }
                 catch (const Base::Exception& e) {
                     QMessageBox::critical(qApp->activeWindow(), QObject::tr("Dimensional constraint"), QString::fromUtf8(e.what()));
@@ -2086,11 +2247,17 @@ void CmdSketcherConstrainRadius::activated(int iMsg)
         else {
             // now dialog was shown so commit the command
             commitCommand();
+            commitNeeded=false;            
         }
-
         //updateActive();
         getSelection().clearSelection();
     }
+    
+    if(commitNeeded)
+        commitCommand();
+    
+    if(updateNeeded)
+        updateActive();
 }
 
 bool CmdSketcherConstrainRadius::isActive(void)
@@ -2159,6 +2326,8 @@ void CmdSketcherConstrainAngle::activated(int iMsg)
             std::swap(GeoId2,GeoId3);
             std::swap(PosId2,PosId3);
         };
+        
+        bool bothexternal=checkBothExternal(GeoId1, GeoId2);
 
         if (isEdge(GeoId1, PosId1) && isEdge(GeoId2, PosId2) && isVertex(GeoId3, PosId3)) {
             double ActAngle = 0.0;
@@ -2190,15 +2359,24 @@ void CmdSketcherConstrainAngle::activated(int iMsg)
             Gui::Command::doCommand(
                 Doc,"App.ActiveDocument.%s.addConstraint(Sketcher.Constraint('AngleViaPoint',%d,%d,%d,%d,%f)) ",
                 selection[0].getFeatName(),GeoId1,GeoId2,GeoId3,PosId3,ActAngle);
-
-            finishDistanceConstraint(this, Obj);
+            
+            if (bothexternal) { // it is a constraint on a external line, make it non-driving
+                const std::vector<Sketcher::Constraint *> &ConStr = Obj->Constraints.getValues();
+                
+                Gui::Command::doCommand(Doc,"App.ActiveDocument.%s.setDriving(%i,%s)",
+                selection[0].getFeatName(),ConStr.size()-1,"False");
+                finishDistanceConstraint(this, Obj,false);
+            }
+            else
+                finishDistanceConstraint(this, Obj,true);
+            
             return;
         };
 
     } else if (SubNames.size() < 3) {
 
-        if (checkBothExternal(GeoId1, GeoId2))
-            return;
+        bool bothexternal=checkBothExternal(GeoId1, GeoId2);
+        
         if (isVertex(GeoId1,PosId1) && isEdge(GeoId2,PosId2)) {
             std::swap(GeoId1,GeoId2);
             std::swap(PosId1,PosId2);
@@ -2260,14 +2438,22 @@ void CmdSketcherConstrainAngle::activated(int iMsg)
                     Doc,"App.ActiveDocument.%s.addConstraint(Sketcher.Constraint('Angle',%d,%d,%d,%d,%f)) ",
                     selection[0].getFeatName(),GeoId1,PosId1,GeoId2,PosId2,ActAngle);
 
-                finishDistanceConstraint(this, Obj);
+                if (bothexternal) { // it is a constraint on a external line, make it non-driving
+                    const std::vector<Sketcher::Constraint *> &ConStr = Obj->Constraints.getValues();
+                    
+                    Gui::Command::doCommand(Doc,"App.ActiveDocument.%s.setDriving(%i,%s)",
+                    selection[0].getFeatName(),ConStr.size()-1,"False");
+                    finishDistanceConstraint(this, Obj,false);
+                }
+                else
+                    finishDistanceConstraint(this, Obj,true);
+        
                 return;
             }
         } else if (isEdge(GeoId1,PosId1)) { // line angle
-            if (GeoId1 < 0) {
+            if (GeoId1 < 0 && GeoId1 >= -2) {
                 QMessageBox::warning(Gui::getMainWindow(), QObject::tr("Wrong selection"),
-                    GeoId1 < -2 ? QObject::tr("Cannot add an angle constraint on an external geometry!")
-                                : QObject::tr("Cannot add an angle constraint on an axis!"));
+                    QObject::tr("Cannot add an angle constraint on an axis!"));
                 return;
             }
 
@@ -2283,7 +2469,16 @@ void CmdSketcherConstrainAngle::activated(int iMsg)
                     Doc,"App.ActiveDocument.%s.addConstraint(Sketcher.Constraint('Angle',%d,%f)) ",
                     selection[0].getFeatName(),GeoId1,ActAngle);
 
-                finishDistanceConstraint(this, Obj);
+                if (GeoId1 < -2) { // it is a constraint on a external line, make it non-driving
+                    const std::vector<Sketcher::Constraint *> &ConStr = Obj->Constraints.getValues();
+                    
+                    Gui::Command::doCommand(Doc,"App.ActiveDocument.%s.setDriving(%i,%s)",
+                    selection[0].getFeatName(),ConStr.size()-1,"False");
+                    finishDistanceConstraint(this, Obj,false);
+                }
+                else
+                    finishDistanceConstraint(this, Obj,true);
+                
                 return;
             }
             else if (geom->getTypeId() == Part::GeomArcOfCircle::getClassTypeId()) {
@@ -2298,7 +2493,16 @@ void CmdSketcherConstrainAngle::activated(int iMsg)
                     Doc,"App.ActiveDocument.%s.addConstraint(Sketcher.Constraint('Angle',%d,%f)) ",
                     selection[0].getFeatName(),GeoId1,angle);
 
-                finishDistanceConstraint(this, Obj);
+                if (GeoId1 < -2) { // it is a constraint on a external line, make it non-driving
+                    const std::vector<Sketcher::Constraint *> &ConStr = Obj->Constraints.getValues();
+                    
+                    Gui::Command::doCommand(Doc,"App.ActiveDocument.%s.setDriving(%i,%s)",
+                    selection[0].getFeatName(),ConStr.size()-1,"False");
+                    finishDistanceConstraint(this, Obj,false);
+                }
+                else
+                    finishDistanceConstraint(this, Obj,true);
+                
                 return;
             }
         }
@@ -2375,7 +2579,7 @@ void CmdSketcherConstrainEqual::activated(int iMsg)
                 return;
             }
             else if (hasAlreadyExternal) {
-                checkBothExternal(-1,-2); // just for printing the error message
+                showNoConstraintBetweenExternal();
                 return;
             }
             else
@@ -2642,10 +2846,10 @@ void CmdSketcherConstrainSnellsLaw::activated(int iMsg)
             std::swap(PosId2,PosId3);
         }
 
+        bool allexternal=false;
         //a bunch of validity checks
         if ((GeoId1 < 0 && GeoId2 < 0 && GeoId3 < 0)) {
-            strError = QObject::tr("Cannot add a constraint between external geometries!", dmbg);
-            throw(Base::Exception(""));
+            allexternal=true;
         }
 
         if (!(isVertex(GeoId1,PosId1) && !isSimpleVertex(Obj, GeoId1, PosId1) &&
@@ -2655,27 +2859,31 @@ void CmdSketcherConstrainSnellsLaw::activated(int iMsg)
             throw(Base::Exception(""));
         };
 
-        //the essence.
-        //Unlike other constraints, we'll ask for a value immediately.
-        QDialog dlg(Gui::getMainWindow());
-        Ui::InsertDatum ui_Datum;
-        ui_Datum.setupUi(&dlg);
-        dlg.setWindowTitle(EditDatumDialog::tr("Refractive index ratio", dmbg));
-        ui_Datum.label->setText(EditDatumDialog::tr("Ratio n2/n1:", dmbg));
-        Base::Quantity init_val;
-        init_val.setUnit(Base::Unit());
-        init_val.setValue(0.0);
+        double n2divn1=0;
+        
+        if(!allexternal){
+            //the essence.
+            //Unlike other constraints, we'll ask for a value immediately.
+            QDialog dlg(Gui::getMainWindow());
+            Ui::InsertDatum ui_Datum;
+            ui_Datum.setupUi(&dlg);
+            dlg.setWindowTitle(EditDatumDialog::tr("Refractive index ratio", dmbg));
+            ui_Datum.label->setText(EditDatumDialog::tr("Ratio n2/n1:", dmbg));
+            Base::Quantity init_val;
+            init_val.setUnit(Base::Unit());
+            init_val.setValue(0.0);
 
-        ui_Datum.labelEdit->setValue(init_val);
-        ui_Datum.labelEdit->setParamGrpPath(QByteArray("User parameter:BaseApp/History/SketcherRefrIndexRatio"));
-        ui_Datum.labelEdit->setToLastUsedValue();
-        ui_Datum.labelEdit->selectNumber();
+            ui_Datum.labelEdit->setValue(init_val);
+            ui_Datum.labelEdit->setParamGrpPath(QByteArray("User parameter:BaseApp/History/SketcherRefrIndexRatio"));
+            ui_Datum.labelEdit->setToLastUsedValue();
+            ui_Datum.labelEdit->selectNumber();
 
-        if (dlg.exec() != QDialog::Accepted) return;
-        ui_Datum.labelEdit->pushToHistory();
+            if (dlg.exec() != QDialog::Accepted) return;
+            ui_Datum.labelEdit->pushToHistory();
 
-        Base::Quantity newQuant = ui_Datum.labelEdit->value();
-        double n2divn1 = newQuant.getValue();
+            Base::Quantity newQuant = ui_Datum.labelEdit->value();
+            n2divn1 = newQuant.getValue();
+        }
 
         //add constraint
         openCommand("add Snell's law constraint");
@@ -2694,6 +2902,13 @@ void CmdSketcherConstrainSnellsLaw::activated(int iMsg)
             Doc,"App.ActiveDocument.%s.addConstraint(Sketcher.Constraint('SnellsLaw',%d,%d,%d,%d,%d,%.12f)) ",
             selection[0].getFeatName(),GeoId1,PosId1,GeoId2,PosId2,GeoId3,n2divn1);
 
+        if (allexternal) { // it is a constraint on a external line, make it non-driving
+            const std::vector<Sketcher::Constraint *> &ConStr = Obj->Constraints.getValues();
+            
+            Gui::Command::doCommand(Doc,"App.ActiveDocument.%s.setDriving(%i,%s)",
+            selection[0].getFeatName(),ConStr.size()-1,"False");
+        }            
+        
         commitCommand();
         updateActive();
 
@@ -2771,7 +2986,7 @@ void CmdSketcherConstrainInternalAlignment::activated(int iMsg)
                 return;
             }
             else if (hasAlreadyExternal) {
-                checkBothExternal(-1,-2); // just for printing the error message
+                showNoConstraintBetweenExternal();
                 return;
             }
             else
diff --git a/src/Mod/Sketcher/Gui/SketcherSettings.ui b/src/Mod/Sketcher/Gui/SketcherSettings.ui
index 5d72e0d608..9bc8607c1b 100644
--- a/src/Mod/Sketcher/Gui/SketcherSettings.ui
+++ b/src/Mod/Sketcher/Gui/SketcherSettings.ui
@@ -6,8 +6,8 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>359</width>
-    <height>586</height>
+    <width>404</width>
+    <height>652</height>
    </rect>
   </property>
   <property name="windowTitle">
@@ -40,7 +40,7 @@
           <property name="toolTip">
            <string>The color of edges being edited</string>
           </property>
-          <property name="color">
+          <property name="color" stdset="0">
            <color>
             <red>255</red>
             <green>255</green>
@@ -73,7 +73,7 @@
           <property name="toolTip">
            <string>The color of vertices being edited</string>
           </property>
-          <property name="color">
+          <property name="color" stdset="0">
            <color>
             <red>255</red>
             <green>255</green>
@@ -106,7 +106,7 @@
           <property name="toolTip">
            <string>The color of edges being edited</string>
           </property>
-          <property name="color">
+          <property name="color" stdset="0">
            <color>
             <red>255</red>
             <green>255</green>
@@ -139,7 +139,7 @@
           <property name="toolTip">
            <string>The color of vertices being edited</string>
           </property>
-          <property name="color">
+          <property name="color" stdset="0">
            <color>
             <red>255</red>
             <green>38</green>
@@ -167,12 +167,32 @@
           </property>
          </widget>
         </item>
+        <item row="9" column="1">
+         <widget class="Gui::PrefColorButton" name="DatumColor">
+          <property name="toolTip">
+           <string>The color of fully constrained geometry in edit mode</string>
+          </property>
+          <property name="color" stdset="0">
+           <color>
+            <red>255</red>
+            <green>38</green>
+            <blue>0</blue>
+           </color>
+          </property>
+          <property name="prefEntry" stdset="0">
+           <cstring>ConstrainedDimColor</cstring>
+          </property>
+          <property name="prefPath" stdset="0">
+           <cstring>View</cstring>
+          </property>
+         </widget>
+        </item>
         <item row="4" column="1">
          <widget class="Gui::PrefColorButton" name="ConstructionColor">
           <property name="toolTip">
            <string>The color of construction geometry in edit mode</string>
           </property>
-          <property name="color">
+          <property name="color" stdset="0">
            <color>
             <red>0</red>
             <green>0</green>
@@ -205,7 +225,7 @@
           <property name="toolTip">
            <string>The color of external geometry in edit mode</string>
           </property>
-          <property name="color">
+          <property name="color" stdset="0">
            <color>
             <red>204</red>
             <green>51</green>
@@ -233,12 +253,25 @@
           </property>
          </widget>
         </item>
+        <item row="7" column="0">
+         <widget class="QLabel" name="label_14">
+          <property name="minimumSize">
+           <size>
+            <width>182</width>
+            <height>0</height>
+           </size>
+          </property>
+          <property name="text">
+           <string>Constraint color</string>
+          </property>
+         </widget>
+        </item>
         <item row="6" column="1">
          <widget class="Gui::PrefColorButton" name="FullyConstrainedColor">
           <property name="toolTip">
            <string>The color of fully constrained geometry in edit mode</string>
           </property>
-          <property name="color">
+          <property name="color" stdset="0">
            <color>
             <red>0</red>
             <green>255</green>
@@ -253,40 +286,7 @@
           </property>
          </widget>
         </item>
-        <item row="7" column="0">
-         <widget class="QLabel" name="label_14">
-          <property name="minimumSize">
-           <size>
-            <width>182</width>
-            <height>0</height>
-           </size>
-          </property>
-          <property name="text">
-           <string>Constraint color</string>
-          </property>
-         </widget>
-        </item>
-        <item row="7" column="1">
-         <widget class="Gui::PrefColorButton" name="ConstrainedColor">
-          <property name="toolTip">
-           <string>The color of fully constrained geometry in edit mode</string>
-          </property>
-          <property name="color">
-           <color>
-            <red>255</red>
-            <green>38</green>
-            <blue>0</blue>
-           </color>
-          </property>
-          <property name="prefEntry" stdset="0">
-           <cstring>ConstrainedIcoColor</cstring>
-          </property>
-          <property name="prefPath" stdset="0">
-           <cstring>View</cstring>
-          </property>
-         </widget>
-        </item>
-        <item row="8" column="0">
+        <item row="9" column="0">
          <widget class="QLabel" name="label_15">
           <property name="minimumSize">
            <size>
@@ -299,27 +299,7 @@
           </property>
          </widget>
         </item>
-        <item row="8" column="1">
-         <widget class="Gui::PrefColorButton" name="DatumColor">
-          <property name="toolTip">
-           <string>The color of fully constrained geometry in edit mode</string>
-          </property>
-          <property name="color">
-           <color>
-            <red>255</red>
-            <green>38</green>
-            <blue>0</blue>
-           </color>
-          </property>
-          <property name="prefEntry" stdset="0">
-           <cstring>ConstrainedDimColor</cstring>
-          </property>
-          <property name="prefPath" stdset="0">
-           <cstring>View</cstring>
-          </property>
-         </widget>
-        </item>
-        <item row="9" column="0">
+        <item row="10" column="0">
          <widget class="QLabel" name="label_16">
           <property name="minimumSize">
            <size>
@@ -332,7 +312,20 @@
           </property>
          </widget>
         </item>
-        <item row="9" column="1">
+        <item row="11" column="0">
+         <widget class="QLabel" name="label_12">
+          <property name="minimumSize">
+           <size>
+            <width>182</width>
+            <height>0</height>
+           </size>
+          </property>
+          <property name="text">
+           <string>Default vertex size</string>
+          </property>
+         </widget>
+        </item>
+        <item row="10" column="1">
          <widget class="Gui::PrefSpinBox" name="SketcherDatumWidth">
           <property name="toolTip">
            <string>The default line thickness for new shapes</string>
@@ -354,8 +347,8 @@
           </property>
          </widget>
         </item>
-        <item row="10" column="0">
-         <widget class="QLabel" name="label_12">
+        <item row="12" column="0">
+         <widget class="QLabel" name="label_13">
           <property name="minimumSize">
            <size>
             <width>182</width>
@@ -363,11 +356,11 @@
            </size>
           </property>
           <property name="text">
-           <string>Default vertex size</string>
+           <string>Default line width</string>
           </property>
          </widget>
         </item>
-        <item row="10" column="1">
+        <item row="11" column="1">
          <widget class="Gui::PrefSpinBox" name="DefaultSketcherVertexWidth">
           <property name="toolTip">
            <string>The default line thickness for new shapes</string>
@@ -389,8 +382,8 @@
           </property>
          </widget>
         </item>
-        <item row="11" column="0">
-         <widget class="QLabel" name="label_13">
+        <item row="13" column="0">
+         <widget class="QLabel" name="label_5">
           <property name="minimumSize">
            <size>
             <width>182</width>
@@ -398,11 +391,28 @@
            </size>
           </property>
           <property name="text">
-           <string>Default line width</string>
+           <string>Cursor text color</string>
           </property>
          </widget>
         </item>
-        <item row="11" column="1">
+        <item row="13" column="1">
+         <widget class="Gui::PrefColorButton" name="CursorTextColor">
+          <property name="color" stdset="0">
+           <color>
+            <red>0</red>
+            <green>0</green>
+            <blue>255</blue>
+           </color>
+          </property>
+          <property name="prefEntry" stdset="0">
+           <cstring>CursorTextColor</cstring>
+          </property>
+          <property name="prefPath" stdset="0">
+           <cstring>View</cstring>
+          </property>
+         </widget>
+        </item>
+        <item row="12" column="1">
          <widget class="Gui::PrefSpinBox" name="DefaultSketcherLineWidth">
           <property name="toolTip">
            <string>The default line thickness for new shapes</string>
@@ -424,30 +434,47 @@
           </property>
          </widget>
         </item>
-        <item row="12" column="0">
-         <widget class="QLabel" name="label_5">
-          <property name="minimumSize">
-           <size>
-            <width>182</width>
-            <height>0</height>
-           </size>
-          </property>
+        <item row="8" column="0">
+         <widget class="QLabel" name="label_8">
           <property name="text">
-           <string>Cursor text color</string>
+           <string>Non-driving Datum color</string>
           </property>
          </widget>
         </item>
-        <item row="12" column="1">
-         <widget class="Gui::PrefColorButton" name="CursorTextColor">
-          <property name="color">
+        <item row="7" column="1">
+         <widget class="Gui::PrefColorButton" name="ConstrainedColor">
+          <property name="toolTip">
+           <string>The color of driving constraints in edit mode</string>
+          </property>
+          <property name="color" stdset="0">
+           <color>
+            <red>255</red>
+            <green>38</green>
+            <blue>0</blue>
+           </color>
+          </property>
+          <property name="prefEntry" stdset="0">
+           <cstring>ConstrainedIcoColor</cstring>
+          </property>
+          <property name="prefPath" stdset="0">
+           <cstring>View</cstring>
+          </property>
+         </widget>
+        </item>
+        <item row="8" column="1">
+         <widget class="Gui::PrefColorButton" name="NonDrivingConstraintColor">
+          <property name="toolTip">
+           <string>The color of non-driving constrains or dimensions in edit mode</string>
+          </property>
+          <property name="color" stdset="0">
            <color>
             <red>0</red>
-            <green>0</green>
+            <green>38</green>
             <blue>255</blue>
            </color>
           </property>
           <property name="prefEntry" stdset="0">
-           <cstring>CursorTextColor</cstring>
+           <cstring>NonDrivingConstrDimColor</cstring>
           </property>
           <property name="prefPath" stdset="0">
            <cstring>View</cstring>
diff --git a/src/Mod/Sketcher/Gui/TaskSketcherConstrains.cpp b/src/Mod/Sketcher/Gui/TaskSketcherConstrains.cpp
index aad748f369..b4ff81ae2f 100644
--- a/src/Mod/Sketcher/Gui/TaskSketcherConstrains.cpp
+++ b/src/Mod/Sketcher/Gui/TaskSketcherConstrains.cpp
@@ -62,7 +62,6 @@ QIcon icon_ ## FUNC( Gui::BitmapFactory().pixmap(ICONSTR) );
     QAction* constr_ ## FUNC = menu.addAction(icon_ ## FUNC,tr(NAMESTR), this, SLOT(FUNC()),    \
         QKeySequence(QString::fromUtf8(Gui::Application::Instance->commandManager().getCommandByName(CMDSTR)->getAccel())));        \
     if(ACTSONSELECTION) constr_ ## FUNC->setEnabled(!items.isEmpty()); else constr_ ## FUNC->setEnabled(true);
-
 /// Defines the member function corresponding to the CONTEXT_ITEM macro
 #define CONTEXT_MEMBER_DEF(CMDSTR,FUNC)                             \
 void ConstraintView::FUNC(){                               \
@@ -72,15 +71,15 @@ void ConstraintView::FUNC(){                               \
 class ConstraintItem : public QListWidgetItem
 {
 public:
-    ConstraintItem(const QIcon & icon, const QString & text,int ConstNbr,Sketcher::ConstraintType t)
-        : QListWidgetItem(icon,text),ConstraintNbr(ConstNbr),Type(t)
+    ConstraintItem(const QIcon & icon, const QString & text,int ConstNbr,Sketcher::ConstraintType t,bool isdriving=true, bool isenforceable=true)
+        : QListWidgetItem(icon,text),ConstraintNbr(ConstNbr),Type(t),isDriving(isdriving),isEnforceable(isenforceable)
     {
-        this->setFlags(this->flags() | Qt::ItemIsEditable);
+        this->setFlags(this->flags() | Qt::ItemIsEditable);        
     }
-    ConstraintItem(const QString & text,int ConstNbr,Sketcher::ConstraintType t)
-        : QListWidgetItem(text),ConstraintNbr(ConstNbr),Type(t)
+    ConstraintItem(const QString & text,int ConstNbr,Sketcher::ConstraintType t,bool isdriving=true, bool isenforceable=true)
+        : QListWidgetItem(text),ConstraintNbr(ConstNbr),Type(t),isDriving(isdriving),isEnforceable(isenforceable)
     {
-        this->setFlags(this->flags() | Qt::ItemIsEditable);
+        this->setFlags(this->flags() | Qt::ItemIsEditable);       
     }
     ~ConstraintItem()
     {
@@ -106,9 +105,12 @@ public:
 
     int ConstraintNbr;
     Sketcher::ConstraintType Type;
+    bool isDriving;
+    bool isEnforceable;
 
 private:
     QVariant quantity;
+    
 };
 
 ConstraintView::ConstraintView(QWidget *parent)
@@ -129,11 +131,32 @@ void ConstraintView::contextMenuEvent (QContextMenuEvent* event)
     CONTEXT_ITEM("Sketcher_SelectElementsAssociatedWithConstraints","Select Elements","Sketcher_SelectElementsAssociatedWithConstraints",doSelectConstraints,true)
     
     menu.addSeparator();
+       
+    if(item) // Non-driving-constraints/measurements
+    {
+        ConstraintItem *it = dynamic_cast<ConstraintItem*>(item);
+        
+        QAction* driven = menu.addAction(it->isDriving?tr("Disable"):tr("Enable"), this, SLOT(updateDrivingStatus()));
+        // if its the right constraint
+        if ((it->Type == Sketcher::Distance ||
+            it->Type == Sketcher::DistanceX ||
+            it->Type == Sketcher::DistanceY ||
+            it->Type == Sketcher::Radius ||
+            it->Type == Sketcher::Angle ||
+            it->Type == Sketcher::SnellsLaw) && it->isEnforceable) { 
 
-    QAction* change = menu.addAction(tr("Change value"), this, SLOT(modifyCurrentItem()));
-    QVariant v = item ? item->data(Qt::UserRole) : QVariant();
-    change->setEnabled(v.isValid());
+            driven->setEnabled(true);    
+        }
+        else{
+            driven->setEnabled(false);   
+        }
+         
 
+        QAction* change = menu.addAction(tr("Change value"), this, SLOT(modifyCurrentItem()));
+        QVariant v = item ? item->data(Qt::UserRole) : QVariant();
+        change->setEnabled(v.isValid() && it->isDriving);
+
+    }
     QAction* rename = menu.addAction(tr("Rename"), this, SLOT(renameCurrentItem())
 #ifndef Q_WS_MAC // on Mac F2 doesn't seem to trigger an edit signal
         ,QKeySequence(Qt::Key_F2)
@@ -149,6 +172,17 @@ void ConstraintView::contextMenuEvent (QContextMenuEvent* event)
 
 CONTEXT_MEMBER_DEF("Sketcher_SelectElementsAssociatedWithConstraints",doSelectConstraints)
 
+void ConstraintView::updateDrivingStatus()
+{
+    QListWidgetItem* item = currentItem();
+    
+    if (item){
+        ConstraintItem *it = dynamic_cast<ConstraintItem*>(item);
+        
+        onUpdateDrivingStatus(item, !it->isDriving);
+    }    
+}
+
 void ConstraintView::modifyCurrentItem()
 {
     /*emit*/itemActivated(currentItem());
@@ -208,6 +242,10 @@ TaskSketcherConstrains::TaskSketcherConstrains(ViewProviderSketch *sketchView)
         ui->listWidgetConstraints, SIGNAL(itemChanged(QListWidgetItem *)),
         this                     , SLOT  (on_listWidgetConstraints_itemChanged(QListWidgetItem *))
        );
+    QObject::connect(
+        ui->listWidgetConstraints, SIGNAL(onUpdateDrivingStatus(QListWidgetItem *, bool)),
+        this                     , SLOT  (on_listWidgetConstraints_updateDrivingStatus(QListWidgetItem *, bool))
+       );
 
     connectionConstraintsChanged = sketchView->signalConstraintsChanged.connect(
         boost::bind(&SketcherGui::TaskSketcherConstrains::slotConstraintsChanged, this));
@@ -293,12 +331,12 @@ void TaskSketcherConstrains::on_listWidgetConstraints_itemActivated(QListWidgetI
     if (!item) return;
 
     // if its the right constraint
-    if (it->Type == Sketcher::Distance ||
+    if ((it->Type == Sketcher::Distance ||
         it->Type == Sketcher::DistanceX ||
         it->Type == Sketcher::DistanceY ||
         it->Type == Sketcher::Radius ||
         it->Type == Sketcher::Angle ||
-        it->Type == Sketcher::SnellsLaw) {
+        it->Type == Sketcher::SnellsLaw) && it->isDriving) {
 
         EditDatumDialog *editDatumDialog = new EditDatumDialog(this->sketchView, it->ConstraintNbr);
         editDatumDialog->exec(false);
@@ -306,6 +344,30 @@ void TaskSketcherConstrains::on_listWidgetConstraints_itemActivated(QListWidgetI
     }
 }
 
+void TaskSketcherConstrains::on_listWidgetConstraints_updateDrivingStatus(QListWidgetItem *item, bool status)
+{
+    ConstraintItem *it = dynamic_cast<ConstraintItem*>(item);
+    if (!item) return;
+    
+    const std::vector< Sketcher::Constraint * > &vals = sketchView->getSketchObject()->Constraints.getValues();
+    
+    try {
+        Gui::Command::openCommand("Modify driving status of constraint");
+        Gui::Command::doCommand(Gui::Command::Doc,"App.ActiveDocument.%s.setDriving(%i,%s)",
+            this->sketchView->getSketchObject()->getNameInDocument(),
+            it->ConstraintNbr,
+            status?"True":"False");
+        Gui::Command::commitCommand();
+        Gui::Command::updateActive();
+    }
+    catch (const Base::Exception& e) {
+        Gui::Command::abortCommand();
+    }
+    
+    slotConstraintsChanged();
+    
+}
+
 void TaskSketcherConstrains::on_listWidgetConstraints_itemChanged(QListWidgetItem *item)
 {
     if (!item || inEditMode)
@@ -381,6 +443,13 @@ void TaskSketcherConstrains::slotConstraintsChanged(void)
     QIcon iaellipsefocus1 ( Gui::BitmapFactory().pixmap("Constraint_InternalAlignment_Ellipse_Focus1") );
     QIcon iaellipsefocus2 ( Gui::BitmapFactory().pixmap("Constraint_InternalAlignment_Ellipse_Focus2") );
     QIcon iaellipseother ( Gui::BitmapFactory().pixmap("Constraint_InternalAlignment") );
+    
+    QIcon hdist_driven ( Gui::BitmapFactory().pixmap("Constraint_HorizontalDistance_Driven") );
+    QIcon vdist_driven( Gui::BitmapFactory().pixmap("Constraint_VerticalDistance_Driven") );
+    QIcon dist_driven ( Gui::BitmapFactory().pixmap("Constraint_Length_Driven") );
+    QIcon radi_driven ( Gui::BitmapFactory().pixmap("Constraint_Radius_Driven") );
+    QIcon angl_driven ( Gui::BitmapFactory().pixmap("Constraint_InternalAngle_Driven") );
+    QIcon snell_driven ( Gui::BitmapFactory().pixmap("Constraint_SnellsLaw_Driven") );
 
     assert(sketchView);
     // Build up ListView with the constraints
@@ -403,6 +472,7 @@ void TaskSketcherConstrains::slotConstraintsChanged(void)
       1 <=> Normal
       2 <=> Datums
       3 <=> Named
+      4 <=> Non-Driving
       */
         switch((*it)->Type){
             case Sketcher::Horizontal:
@@ -442,48 +512,48 @@ void TaskSketcherConstrains::slotConstraintsChanged(void)
                     ui->listWidgetConstraints->addItem(new ConstraintItem(symm,name,i-1,(*it)->Type));
                 break;
             case Sketcher::Distance:
-                if (Filter<3 || !(*it)->Name.empty()) {
-                    ConstraintItem* item = new ConstraintItem(dist,name,i-1,(*it)->Type);
+                if (((Filter<3 || !(*it)->Name.empty())) || (Filter==4 && !(*it)->isDriving)) {
+                    ConstraintItem* item = new ConstraintItem((*it)->isDriving?dist:dist_driven,name,i-1,(*it)->Type,(*it)->isDriving, ((*it)->First>=0 || (*it)->Second>=0 || (*it)->Third>=0));
                     name = QString::fromLatin1("%1 (%2)").arg(name).arg(Base::Quantity((*it)->Value,Base::Unit::Length).getUserString());
-                    item->setData(Qt::UserRole, name);
+                    item->setData(Qt::UserRole, name);                    
                     ui->listWidgetConstraints->addItem(item);
                 }
                 break;
             case Sketcher::DistanceX:
-                if (Filter<3 || !(*it)->Name.empty()) {
-                    ConstraintItem* item = new ConstraintItem(hdist,name,i-1,(*it)->Type);
+                if (((Filter<3 || !(*it)->Name.empty())) || (Filter==4 && !(*it)->isDriving)) {
+                    ConstraintItem* item = new ConstraintItem((*it)->isDriving?hdist:hdist_driven,name,i-1,(*it)->Type,(*it)->isDriving, ((*it)->First>=0 || (*it)->Second>=0 || (*it)->Third>=0));
                     name = QString::fromLatin1("%1 (%2)").arg(name).arg(Base::Quantity(std::abs((*it)->Value),Base::Unit::Length).getUserString());
                     item->setData(Qt::UserRole, name);
                     ui->listWidgetConstraints->addItem(item);
                 }
                 break;
             case Sketcher::DistanceY:
-                if (Filter<3 || !(*it)->Name.empty()) {
-                    ConstraintItem* item = new ConstraintItem(vdist,name,i-1,(*it)->Type);
+                if (((Filter<3 || !(*it)->Name.empty())) || (Filter==4 && !(*it)->isDriving)) {
+                    ConstraintItem* item = new ConstraintItem((*it)->isDriving?vdist:vdist_driven,name,i-1,(*it)->Type,(*it)->isDriving, ((*it)->First>=0 || (*it)->Second>=0 || (*it)->Third>=0));
                     name = QString::fromLatin1("%1 (%2)").arg(name).arg(Base::Quantity(std::abs((*it)->Value),Base::Unit::Length).getUserString());
                     item->setData(Qt::UserRole, name);
                     ui->listWidgetConstraints->addItem(item);
                 }
                 break;
             case Sketcher::Radius:
-                if (Filter<3 || !(*it)->Name.empty()) {
-                    ConstraintItem* item = new ConstraintItem(radi,name,i-1,(*it)->Type);
+                if (((Filter<3 || !(*it)->Name.empty())) || (Filter==4 && !(*it)->isDriving)) {
+                    ConstraintItem* item = new ConstraintItem((*it)->isDriving?radi:radi_driven,name,i-1,(*it)->Type,(*it)->isDriving, ((*it)->First>=0 || (*it)->Second>=0 || (*it)->Third>=0));
                     name = QString::fromLatin1("%1 (%2)").arg(name).arg(Base::Quantity((*it)->Value,Base::Unit::Length).getUserString());
                     item->setData(Qt::UserRole, name);
                     ui->listWidgetConstraints->addItem(item);
                 }
                 break;
             case Sketcher::Angle:
-                if (Filter<3 || !(*it)->Name.empty()) {
-                    ConstraintItem* item = new ConstraintItem(angl,name,i-1,(*it)->Type);
+                if (((Filter<3 || !(*it)->Name.empty())) || (Filter==4 && !(*it)->isDriving)) {
+                    ConstraintItem* item = new ConstraintItem((*it)->isDriving?angl:angl_driven,name,i-1,(*it)->Type,(*it)->isDriving, ((*it)->First>=0 || (*it)->Second>=0 || (*it)->Third>=0));
                     name = QString::fromLatin1("%1 (%2)").arg(name).arg(Base::Quantity(Base::toDegrees<double>(std::abs((*it)->Value)),Base::Unit::Angle).getUserString());
                     item->setData(Qt::UserRole, name);
                     ui->listWidgetConstraints->addItem(item);
                 }
                 break;
             case Sketcher::SnellsLaw:
-                if (Filter<3 || !(*it)->Name.empty()) {
-                    ConstraintItem* item = new ConstraintItem(snell,name,i-1,(*it)->Type);
+                if (((Filter<3 || !(*it)->Name.empty())) || (Filter==4 && !(*it)->isDriving)) {
+                    ConstraintItem* item = new ConstraintItem((*it)->isDriving?snell:snell_driven,name,i-1,(*it)->Type,(*it)->isDriving, ((*it)->First>=0 || (*it)->Second>=0 || (*it)->Third>=0));
 
                     double v = (*it)->Value;
                     double n1 = 1.0;
diff --git a/src/Mod/Sketcher/Gui/TaskSketcherConstrains.h b/src/Mod/Sketcher/Gui/TaskSketcherConstrains.h
index 7d78060007..18eec1786e 100644
--- a/src/Mod/Sketcher/Gui/TaskSketcherConstrains.h
+++ b/src/Mod/Sketcher/Gui/TaskSketcherConstrains.h
@@ -48,11 +48,15 @@ public:
 protected:
     void contextMenuEvent (QContextMenuEvent* event);
 
+Q_SIGNALS:
+    void onUpdateDrivingStatus(QListWidgetItem *item, bool status);
+
 protected Q_SLOTS:
     void modifyCurrentItem();
     void renameCurrentItem();
     void deleteSelectedItems();
     void doSelectConstraints();
+    void updateDrivingStatus();
 };
 
 class TaskSketcherConstrains : public Gui::TaskView::TaskBox, public Gui::SelectionObserver
@@ -74,6 +78,7 @@ public Q_SLOTS:
     void on_listWidgetConstraints_itemSelectionChanged(void); 
     void on_listWidgetConstraints_itemActivated(QListWidgetItem *item);
     void on_listWidgetConstraints_itemChanged(QListWidgetItem * item);
+    void on_listWidgetConstraints_updateDrivingStatus(QListWidgetItem *item, bool status);
 
 protected:
     void changeEvent(QEvent *e);
diff --git a/src/Mod/Sketcher/Gui/TaskSketcherConstrains.ui b/src/Mod/Sketcher/Gui/TaskSketcherConstrains.ui
index cb56a02609..3e3ba1f9e6 100644
--- a/src/Mod/Sketcher/Gui/TaskSketcherConstrains.ui
+++ b/src/Mod/Sketcher/Gui/TaskSketcherConstrains.ui
@@ -6,7 +6,7 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>176</width>
+    <width>212</width>
     <height>288</height>
    </rect>
   </property>
@@ -26,7 +26,7 @@
      <item>
       <widget class="QComboBox" name="comboBoxFilter">
        <property name="currentIndex">
-        <number>1</number>
+        <number>0</number>
        </property>
        <item>
         <property name="text">
@@ -48,6 +48,11 @@
          <string>Named</string>
         </property>
        </item>
+       <item>
+        <property name="text">
+         <string>Non-Driving</string>
+        </property>
+       </item>
       </widget>
      </item>
     </layout>
diff --git a/src/Mod/Sketcher/Gui/ViewProviderSketch.cpp b/src/Mod/Sketcher/Gui/ViewProviderSketch.cpp
index fee2b6431d..3303ee392f 100644
--- a/src/Mod/Sketcher/Gui/ViewProviderSketch.cpp
+++ b/src/Mod/Sketcher/Gui/ViewProviderSketch.cpp
@@ -117,18 +117,19 @@
 using namespace SketcherGui;
 using namespace Sketcher;
 
-SbColor ViewProviderSketch::VertexColor           (1.0f,0.149f,0.0f);   // #FF2600 -> (255, 38,  0)
-SbColor ViewProviderSketch::CurveColor            (1.0f,1.0f,1.0f);     // #FFFFFF -> (255,255,255)
-SbColor ViewProviderSketch::CurveDraftColor       (0.0f,0.0f,0.86f);    // #0000DC -> (  0,  0,220)
-SbColor ViewProviderSketch::CurveExternalColor    (0.8f,0.2f,0.6f);     // #CC3399 -> (204, 51,153)
-SbColor ViewProviderSketch::CrossColorH           (0.8f,0.4f,0.4f);     // #CC6666 -> (204,102,102)
-SbColor ViewProviderSketch::CrossColorV           (0.4f,0.8f,0.4f);     // #66CC66 -> (102,204,102)
-SbColor ViewProviderSketch::FullyConstrainedColor (0.0f,1.0f,0.0f);     // #00FF00 -> (  0,255,  0)
-SbColor ViewProviderSketch::ConstrDimColor        (1.0f,0.149f,0.0f);   // #FF2600 -> (255, 38,  0)
-SbColor ViewProviderSketch::ConstrIcoColor        (1.0f,0.149f,0.0f);   // #FF2600 -> (255, 38,  0)
-SbColor ViewProviderSketch::PreselectColor        (0.88f,0.88f,0.0f);   // #E1E100 -> (225,225,  0)
-SbColor ViewProviderSketch::SelectColor           (0.11f,0.68f,0.11f);  // #1CAD1C -> ( 28,173, 28)
-SbColor ViewProviderSketch::PreselectSelectedColor(0.36f,0.48f,0.11f);  // #5D7B1C -> ( 93,123, 28)
+SbColor ViewProviderSketch::VertexColor                 (1.0f,0.149f,0.0f);   // #FF2600 -> (255, 38,  0)
+SbColor ViewProviderSketch::CurveColor                  (1.0f,1.0f,1.0f);     // #FFFFFF -> (255,255,255)
+SbColor ViewProviderSketch::CurveDraftColor             (0.0f,0.0f,0.86f);    // #0000DC -> (  0,  0,220)
+SbColor ViewProviderSketch::CurveExternalColor          (0.8f,0.2f,0.6f);     // #CC3399 -> (204, 51,153)
+SbColor ViewProviderSketch::CrossColorH                 (0.8f,0.4f,0.4f);     // #CC6666 -> (204,102,102)
+SbColor ViewProviderSketch::CrossColorV                 (0.4f,0.8f,0.4f);     // #66CC66 -> (102,204,102)
+SbColor ViewProviderSketch::FullyConstrainedColor       (0.0f,1.0f,0.0f);     // #00FF00 -> (  0,255,  0)
+SbColor ViewProviderSketch::ConstrDimColor              (1.0f,0.149f,0.0f);   // #FF2600 -> (255, 38,  0)
+SbColor ViewProviderSketch::ConstrIcoColor              (1.0f,0.149f,0.0f);   // #FF2600 -> (255, 38,  0)
+SbColor ViewProviderSketch::NonDrivingConstrDimColor    (0.0f,0.149f,1.0f);   // #0026FF -> (  0, 38,255)
+SbColor ViewProviderSketch::PreselectColor              (0.88f,0.88f,0.0f);   // #E1E100 -> (225,225,  0)
+SbColor ViewProviderSketch::SelectColor                 (0.11f,0.68f,0.11f);  // #1CAD1C -> ( 28,173, 28)
+SbColor ViewProviderSketch::PreselectSelectedColor      (0.36f,0.48f,0.11f);  // #5D7B1C -> ( 93,123, 28)
 // Variables for holding previous click
 SbTime  ViewProviderSketch::prvClickTime;
 SbVec3f ViewProviderSketch::prvClickPoint;
@@ -2302,9 +2303,9 @@ void ViewProviderSketch::updateColor(void)
         else {
             if (hasDatumLabel) {
                 SoDatumLabel *l = dynamic_cast<SoDatumLabel *>(s->getChild(CONSTRAINT_SEPARATOR_INDEX_MATERIAL_OR_DATUMLABEL));
-                l->textColor = ConstrDimColor;
+                l->textColor = constraint->isDriving?ConstrDimColor:NonDrivingConstrDimColor;
             } else if (hasMaterial) {
-                m->diffuseColor = ConstrDimColor;
+                m->diffuseColor = constraint->isDriving?ConstrDimColor:NonDrivingConstrDimColor;
             }
         }
     }
@@ -2383,6 +2384,9 @@ QColor ViewProviderSketch::constrColor(int constraintId)
     static QColor constrIcoColor((int)(ConstrIcoColor [0] * 255.0f),
                                  (int)(ConstrIcoColor[1] * 255.0f),
                                  (int)(ConstrIcoColor[2] * 255.0f));
+    static QColor nonDrivingConstrIcoColor((int)(NonDrivingConstrDimColor[0] * 255.0f),
+                                 (int)(NonDrivingConstrDimColor[1] * 255.0f),
+                                 (int)(NonDrivingConstrDimColor[2] * 255.0f));
     static QColor constrIconSelColor ((int)(SelectColor[0] * 255.0f),
                                       (int)(SelectColor[1] * 255.0f),
                                       (int)(SelectColor[2] * 255.0f));
@@ -2390,12 +2394,17 @@ QColor ViewProviderSketch::constrColor(int constraintId)
                                          (int)(PreselectColor[1] * 255.0f),
                                          (int)(PreselectColor[2] * 255.0f));
 
+    const std::vector<Sketcher::Constraint *> &constraints = getSketchObject()->Constraints.getValues();
+    
     if (edit->PreselectConstraintSet.count(constraintId))
         return constrIconPreselColor;
     else if (edit->SelConstraintSet.find(constraintId) != edit->SelConstraintSet.end())
         return constrIconSelColor;
+    else if(!constraints[constraintId]->isDriving)
+        return nonDrivingConstrIcoColor;
     else
         return constrIcoColor;
+        
 }
 
 int ViewProviderSketch::constrColorPriority(int constraintId)
@@ -3872,7 +3881,7 @@ void ViewProviderSketch::rebuildConstraintsVisual(void)
         // every constrained visual node gets its own material for preselection and selection
         SoMaterial *mat = new SoMaterial;
         mat->ref();
-        mat->diffuseColor = ConstrDimColor;
+        mat->diffuseColor = (*it)->isDriving?ConstrDimColor:NonDrivingConstrDimColor;
         // Get sketch normal
         Base::Vector3d RN(0,0,1);
 
@@ -3895,7 +3904,7 @@ void ViewProviderSketch::rebuildConstraintsVisual(void)
                 SoDatumLabel *text = new SoDatumLabel();
                 text->norm.setValue(norm);
                 text->string = "";
-                text->textColor = ConstrDimColor;
+                text->textColor = (*it)->isDriving?ConstrDimColor:NonDrivingConstrDimColor;;
                 text->size.setValue(fontSize);
                 text->useAntialiasing = false;
                 SoAnnotation *anno = new SoAnnotation();
@@ -4145,6 +4154,10 @@ bool ViewProviderSketch::setEdit(int ModNum)
     color = (unsigned long)(ConstrIcoColor.getPackedValue());
     color = hGrp->GetUnsigned("ConstrainedIcoColor", color);
     ConstrIcoColor.setPackedValue((uint32_t)color, transparency);
+    // set non-driving constraint color
+    color = (unsigned long)(NonDrivingConstrDimColor.getPackedValue());
+    color = hGrp->GetUnsigned("NonDrivingConstrDimColor", color);
+    NonDrivingConstrDimColor.setPackedValue((uint32_t)color, transparency);    
     // set the external geometry color
     color = (unsigned long)(CurveExternalColor.getPackedValue());
     color = hGrp->GetUnsigned("ExternalColor", color);
diff --git a/src/Mod/Sketcher/Gui/ViewProviderSketch.h b/src/Mod/Sketcher/Gui/ViewProviderSketch.h
index 7761d98d9f..ac30c83eca 100644
--- a/src/Mod/Sketcher/Gui/ViewProviderSketch.h
+++ b/src/Mod/Sketcher/Gui/ViewProviderSketch.h
@@ -349,6 +349,7 @@ protected:
     static SbColor FullyConstrainedColor;
     static SbColor ConstrDimColor;
     static SbColor ConstrIcoColor;
+    static SbColor NonDrivingConstrDimColor;
     static SbColor PreselectColor;
     static SbColor SelectColor;
     static SbColor PreselectSelectedColor;